Estate tax FAQ

What is the estate tax?

Does the state of Washington have an inheritance or estate tax?

Washington does not have an inheritance tax. Washington does have an estate tax.

During a general election in November 1981, the voters repealed an inheritance tax and enacted an estate tax. The change from an inheritance tax to an estate tax became effective January 1, 1982. Due to this change, Washington no longer has an inheritance tax waiver.

In general terms, an inheritance tax is a tax on the beneficiaries of an estate whereas an estate tax is a tax on the decedent’s estate.

If you are a person living in Washington who inherits property or money, you do not owe Washington taxes on your inheritance.

What is the estate tax?

The estate tax is a tax on the right to transfer property at the time of death. A person residing in Washington or a non-resident who owns property in Washington may owe an estate tax depending on the value of their estate.

When is a Washington estate tax return required?

You are required to file a Washington estate tax return if a decedent's gross value of all their property, wherever located, is over the filing threshold (fair market value without any deductions) and either of the following applies:

  • They are a Washington resident, or
  • They are a non-resident but own real estate or tangible personal property located in Washington on their date of death.

If one of the above requirements are met, a filing is required even if no tax is due.

If the decedent's estate is under the filing threshold, an estate tax return does not need to be filed and no estate taxes would be due.

If the decedent and the surviving spouse own a personal residence, the decedent’s portion of the personal residence may be excluded from the gross estate value when determining if the estate meets the filing threshold, if it qualifies. See our Estate tax spousal personal residence exclusion page for more information.

"Property" includes but is not limited to: 

  • Real estate. 
  • Stocks. 
  • Bonds. 
  • Interest in business entities. 
  • Cash. 
  • Notes. 
  • Life insurance policies. 
  • Assets owned jointly with a spouse. 
  • Assets owned jointly with others. 
  • Vehicles. 
  • Recreational vehicles. 
  • Royalties. 
  • Pension plans. 
  • Refunds.
  • Assets held in trust. 
  • Annuities, etc.
What is the estate tax filing threshold?

The executor must file a Washington estate tax return if the decedent owned property in Washington state and the gross estate exceeds the filing threshold.

For estate tax filing amounts, see the Filing thresholds and exclusion amounts table.

Note: If the gross estate is over the filing threshold an estate tax return is required, even if no tax is due.

What is the estate tax applicable exclusion amount?

The applicable exclusion amount is an amount deducted prior to calculating estate tax due. For dates of death of January 1, 2014, and after, the exclusion amount may be adjusted annually using the Seattle-Tacoma-Bremerton metropolitan area October consumer price index.

For applicable exclusion amounts, see the Filing thresholds and exclusion amounts table.

What are the estate tax funds used for?

The estate tax funds are deposited into the Education Legacy Trust Fund.

The Education Legacy Trust Fund provides funding for:

  • The student achievement fund for reducing class sizes, professional development of teachers, extended learning such as before- and after-school programs, and pre-kindergarten learning.
  • Learning assistance program to help kindergarten through 12th-grade students who are not up to standards.
  • Higher education (which includes monies for financial aid, supporting additional enrollment of students, adult basic education programs in community colleges, work-study programs, etc).
What are my responsibilities as a personal representative or executor of an estate?

When you are appointed as the Personal Representative of an estate, you are now an officer of, and responsible for, the proper administration of the estate’s assets. It is recommended that you seek an attorney's advice on all matters concerning the estate.

Here are a few items you should pay special attention to:

  • Immediately take possession of all of the decedent's assets now belonging to the estate.
  • If the estate is probated, file an inventory with the court listing the estimated values of all of the estate's assets as of the date of decedent's death. However, please note that the inventory and appraisement is not valid supporting documentation for filing an estate tax return.
  • Keep the money and property of the estate separate from your own assets and from any other person's assets. Do not commingle or mix assets of the estate in your personal bank or brokerage accounts. Do not mix any estate money with your own or anyone else's.
  • Do not lend funds of the estate to anyone. Never borrow money from the estate for your personal use.
  • Make estate checks payable to the provider of goods or services, not to "cash" or yourself. Keep estate funds in accounts for which the financial institution provides you a written record showing the date, payee, and amount for each disbursement from the account. The record may be an original canceled check, a copy of the canceled check showing it has cleared the bank, or information printed in a regular statement from the financial institution. Keep accurate records of all receipts of funds. Every receipt and disbursement must be separately itemized. Avoid cash transactions.
  • Do not pay any bill of the estate without determining that you have the authority to do so. Use estate funds, not your own funds, to pay estate expenses whenever possible. If you have paid estate expenses, such as funeral expenses, from your own funds, and if you have a receipt or other proof of the payment, you may reimburse yourself from estate funds. Keep all payment proofs as documentation. If the decedent owed a debt to you, you must have written documentation proving the debt is due before you pay that debt.
  • Do not give or distribute any estate property to any heirs or other persons without the final determination or release of the estate’s obligations.
  • You may be required and should be able to file an accounting of all receipts and expenditures in the estate. The accounting record must track and document all assets on hand at the beginning and end of the accounting period. Written proofs of payment and the first and final statements for each bank or other account in the estate must be included in the estate’s accounting records.

The estate tax section employees are not attorney’s, and cannot provide legal advice. The above are general guidelines all personal representatives should follow in their duties as an officer of the estate.

How do I file the estate tax return?

What is the due date for the estate tax return?

The due date of the Washington State Estate and Transfer Tax Return is nine months after the date of death.

A timely filed extension application will automatically extend the return due date six months.

Note: Any tax due must be paid within the nine months after the date of death or interest will accrue.

How do I file for an extension or an additional extension of the estate tax return?

If you need more time to file, you can apply for a six-month extension of time to file. Approval of an extension of time to file the Washington estate tax return does not grant additional time to pay the estate tax. We recommend submitting an estimated tax payment with the extension if the estate anticipates there will be tax due. Any amounts that remain unpaid after the nine-month due date will accrue daily interest. For interest rates, see our interest rate table.

There are two different ways to apply for an extension of time to file the Washington estate tax return.

To request an additional extension in excess of the six month extension submit an application using our My DOR services, or submit Application for Extension of Time to File a Washington State Estate and Transfer Tax Return along with a statement explaining in detail why it is impossible or impractical to file by the due date.

Please note, an additional extension will not be granted unless the executor is abroad. Be sure to mark the additional extension box and enter the date of the extension on the application form.

Note: Payment received after the original nine month due date will accrue interest. One of the following items must be received by the original nine month due date:

  • A request for an extension to file the Washington estate tax return and estate tax payment, if applicable.
  • The Washington estate tax return and an estimated tax payment, if applicable.
What should I do if I previously filed an extension and now I know the estate is under the filing threshold?
Send us a short letter, or secure message using our My DOR services, stating this fact. We will close our file.
How is the estate tax calculated?

The tax is calculated using the Washington taxable estate and Table W. The Washington taxable estate is the gross estate less all allowable deductions, including the applicable exclusion amount.

What are the estate tax rates for deaths on or after January 1, 2014?

The tax rates range from 10% to 20% of the Washington taxable estate. The taxes are calculated on a graduated scale; each range is taxed at a different rate. See Table W-Computation of Washington estate tax.

Note: The Washington taxable estate is the amount after all allowable deductions, including the applicable exclusion amount.

How do I know what the Washington taxable estate is?
To determine the Washington taxable estate, take the gross estate and subtract any allowable expenses and deductions. The allowable expenses and deductions include items such as the decedent's funeral expenses, costs of administering the estate, any debts of the decedent (mortgages, liens, outstanding bills), bequests to a spouse, gifts to charity, the farm deduction (if eligible), the qualified family-owned business interests deduction (if eligible), and the applicable exclusion amount.
What documentation should I include with the estate tax return?

Before sending the filing, please read the following:

What to include when filing

These documents can now be submitted with your electronic return using our new My DOR services. If sending these documents in the mail, please assemble in the order listed below (unstapled, no binding, and no tabs):

  • Payment made payable to Washington State Department of Revenue, if applicable.
  • Original Washington State Estate and Transfer Tax Return signed by the executor.
    • Include the first three pages of the form and any of the completed Washington return schedules.
  • Addendum(s), if applicable.
  • Copy of the filed Federal Form 706, if applicable.
    • Include the first four pages of the form and any completed 706 return schedules.
  • Copy of Death Certificate.
  • Copy of Letters of Administration/Testamentary, if applicable.
  • Copy of Will, if applicable.
  • Copy of Trust(s), if applicable.
  • Copy of gift tax return(s) (Federal Form 709), if applicable.
  • All supporting documentation for the completed return schedules (one copy of each):
    • Appraisals.
    • Brokerage statements or valuation software reports.
    • Financial or bank statements.
    • Federal Form 712.
    • Business valuations, especially for closely-held or non-publicly traded businesses.
    • Any other type of document or calculation supporting the value reported on a schedule.

Note: All documentation must reflect the proper actual or fair market value of an asset as of the valuation date. For most estates, the valuation date will be the date of death of the decedent. However, if alternate valuation is elected, then assets will have two valuation dates; the date of death and typically a date six months after the date of death (see Internal Revenue Code § 2032 for further clarification). When alternate valuation is reported, two sets of supporting documentation must be sent; one showing date of death values and one showing values as of the alternate valuation date.

Where do I mail estate tax filing (extension, return, etc.)?

Mail extensions, estate tax returns and estate tax correspondence to:

Mailing address:

Washington State Department of Revenue
PO Box 47474
Olympia WA 98504-7474

To overnight an item, the address is as follows:

Private carrier / courier service:
Washington State Department of Revenue Estate Tax
Attn Treasury Management
6500 Linderson Way SW Ste 227
Tumwater WA 98501-6561

Note: Extensions, estate tax returns, and payments received are receipted by the postmark date. It is not necessary to overnight items.

An extension form, with no estimated payment due, may be faxed to 360-534-1499.

Where do I send the Federal Estate Tax Closing Document after I receive it from the Internal Revenue Service (IRS)?

The IRS closing document can be sent to us via secure message, using our My DOR services, or mailed to:

Washington State Department of Revenue
PO Box 47474
Olympia WA 98504-7474

or faxed to 360-534-1499.

How do I pay the estate tax? Who do I make the check payable to and when is the payment due?

To pay the estate tax, send the payment with either a timely filed extension application or the Washington State Estate and Transfer Tax Return.

You can make a payment using our My DOR services, or you can mail the payment and form to:

Washington State Department of Revenue
PO Box 47474
Olympia WA 98504-7474

Make the check payable to: Washington State Department of Revenue.

The estate has nine months from the date of death to pay any tax due. If the estate tax liability is unknown at the nine month due date an estimated tax payment should be made. An extension to file does not give an estate an extension to pay. Interest accrues on any unpaid tax outstanding after the nine month due date.

An estate that includes a qualifying closely-held business may be able to enter an installment payment plan for the portion of taxes attributable to the closely-held business.

What do we do if we are filing and/or paying late?

If an estate is unable to file a timely return, an Application for Extension of Time to File form (either the Washington form or a copy of the Federal Form 4768, if applicable) must be submitted prior to the due date of the estate tax return. For the fastest service, you can file your application for an extension of time to file using our My DOR services.

For any late payment of estate tax, interest should be included with the payment. Interest accrues daily on any unpaid principal. The interest is calculated using simple interest, not compound interest. For assistance with computing interest on an estate tax return, call the estate tax section at 360-704-5906.

Can I use the commercially available Federal Form 706 preparation software to complete the schedules for a Washington only filing of an estate tax return?

You may use the software to complete the schedules only. You must complete the first three pages of the Washington estate tax return and any applicable addendums. If you are filing the 706, you will need to include two sets of schedules (one for the Washington return and one for the 706).

Alternatively, you can file your return using our My DOR services.

What is the interest rate for estate tax?

The interest rate for estate tax changes annually. See our interest rate table for current rates. Interest accrues daily on any unpaid principal. The interest is calculated using simple interest, not compound interest. For assistance with computing interest on an estate tax return, call the estate tax section at 360-704-5906, select option 1.

If you file your return electronically using our new My DOR services, your interest will be estimated for you, if due.

What is the late payment penalty or late filing penalty?

There is no late payment penalty. Interest will accrue on any late payment.

A late filing penalty will apply only if the department notifies the executor in writing that we have determined a filing is required prior to the estate voluntarily notifying us a filing is required (e.g. written notification, filed extension, filed return). If a penalty is applied, it is 5% of the tax due per month (up to 25% or $1,500, whichever is less).

How do I amend the estate tax return?

Complete a new estate tax return with the “Amended Return” box checked. The first three return pages, along with any other schedule and/or addendum pages that have been changed, must be sent with the applicable supporting documentation showing why the return is being amended. We do not need a duplicate copy of the original return, only the pages that have been changed and documentation explaining those changes.

If you prefer, you can file an amended estate tax return using our My DOR services.

 

Who should sign the estate tax return? How do I sign an electronic return?

The executor (personal representative) is the person that is required to file the return and is required to sign the return to make it a valid filing. If there are multiple executors, the primary executor should be listed on the front of the return (for paper returns) or first one listed (for electronic returns). While we would prefer that the primary executor sign the return, any of the executors may sign the return for it to be valid.  

The reason for a primary executor, is if we need to send a refund check, we can only mail that check to one executor’s address. All executors will be mailed a letter explaining the refund, but the refund check itself can only go to one address.

For estate tax returns filed electronically, there is no way to enter an electronic signature. If the executor submits the return, they will mark the return, “under penalty of law” that they are the legal executor, and the filing is correct and valid. The executor’s mark and their submitter information is the executor’s signature. If the preparer submits the return, once they mark the “I am authorized” and enter their submitter information a letter will be sent to the executor(s). At least one executor, must review and attest that the information on that letter is accurate. They must return the signed letter (mail, email, web message) and that is the executor’s signature that the return or amended return is valid.

Remember, when filing via paper, any necessary addendums must be signed by the executor as well. For electronic filings, the signature of the executor when submitting the return themselves, or the attestation letter, is the signature for the addendums as well.

What assets should be reported on the estate tax return?

What assets should be included in the estate? Is it different for a married couple?

All assets owned by the decedent on the date of death should be included in the estate. All assets, even if located in another state, should be reported on the estate tax return (see the Estate tax apportionment for out of state property page).

For the estate of a married decedent, all of the community property and all of the decedent’s separate property are reported on the estate tax return. The community property assets are then reduced by 50% to reflect the decedent’s share of the property. Even if the entire estate will pass to the surviving spouse and no taxes may be due, an estate tax return must be filed if the decedent’s half of the community property, plus the decedent’s separate property, meets the filing threshold.

How do I report the assets for a married couple that die close together?

Per RCW 11.05A.040, a spouse is determined to predecease the other spouse when they die within 120 hours (5 days) of each other. However, per RCW 11.05A.060, if the governing document (Last Will or Trust), explicitly lists a different period of time (such as 30 days), then that time period determines when a spouse predeceased another spouse.

For spouses that die within the designated period above (5 days unless explicitly stated otherwise), each spouse is treated as the surviving spouse. All assets that the spouse owns as of the date of their death is valued as of that date and reported on the estate tax return. No marital deduction or QTIP election on Schedule M is allowed since it is presumed the other spouse predeceased the surviving spouse. For community property assets, the full value would be shown on the gross estate schedules and a reduction of the one-half community ownership interest would be shown below the asset. While the same assets would be reported on each spouse’s return and reduced by the one-half community ownership interest, the value of each asset may not be the same amount, since each would be valued as of their fair market value of that spouse’s date of death.

For spouses that die after the designated period above (5 days unless explicitly stated otherwise), then one spouse is treated as being the predeceased spouse. The predeceased spouse would report the full value of all community property and any separate property on the gross estate schedules. Any community property asset would be reduced by the one-half community property interest. A marital deduction or QTIP election would be allowed on Schedule M. The surviving spouse would report their full value of their assets owned (their one-half community property ownership interest and all separate property) plus any assets they received from the predeceased spouse (marital deduction and QTIP elected assets).

Do I have to include out of state property on the estate tax return?

Yes. All property owned by a decedent must be included on the estate tax return. The estate tax is calculated on the entire estate as if all property is in Washington, then a calculation is done to apportion the tax between the Washington property and the out of state property.

The decedent’s state of domicile at the time of death is what determines if property is in state or out of state property. For a Washington domiciled decedent, any tangible personal property located outside of Washington and any real property located outside of Washington are considered out of state property. For an out of state domiciled decedent, all intangible property, any tangible property located outside of Washington, and any real property located outside of Washington, are considered out of state property.

For more details, see the Estate tax apportionment for out of state property page.

How do I value the assets in the estate?

All assets owned by a decedent are valued at their actual value or fair market value for the valuation date.

The “actual value” of an asset is its cash value or unpaid principal plus any interest accrued to the valuation date.

The “fair market value” is the price at which property would change hands between a willing buyer and a willing seller, neither being under any compulsion to buy or sell and both having reasonable knowledge of the relevant facts. The fair market value would be a sale in an arm’s-length transaction and never determined by a forced sale. Fair market value for a business entity would include any goodwill inherent in the business. For most stocks and bonds, the fair market value is the mean between the highest and lowest selling prices quoted on the valuation date.

The “valuation date” is the date of death of the decedent. However, an alternate value date (six months after the date of death) may be elected. See the instructions for the estate tax return to determine if alternate value may be elected for an estate.

When filing the estate tax return, be sure to include all supporting documentation showing the actual or fair market value. Supporting documentation can include, but is not limited to, real estate appraisals, date of death brokerage statements, and business appraisals.

How do I determine the value of real estate included in the estate?

The best way to determine the value of real estate is an actual arms-length sale within a reasonable time after the date of death of the decedent. When real estate is not sold, the way to determine fair market value is through the use of a certified appraisal.

To locate a certified appraiser in the real estate's city and state, search using the FHA's search for appraisers tool.

Are gifts taxable for Washington estate tax purposes, if so, where do I report gifts on the estate tax return?

Generally, outright gifts given prior to the date of death are not taxable for Washington estate tax purposes.

However, federal gift tax paid, or payable, within three years of the date of death is included as an asset of the estate on Schedule G - Transfers During Decedent’s Life. The federal gift tax paid or payable is reported on the schedule, not the amount of the gift.

Also, any transfers that meet one of the four Internal Revenue Code provisions listed below are considered part of the decedent’s estate because the decedent retained a life interest. If the decedent had any of these four types of assets prior to death and gave the asset outright within three years of death, those gifts are added back into the value of the gross estate and reported on Schedule G - Transfers During Decedent’s Life.

The IRC provisions are:

  1. 26 USC §2036 - Transfers with retained life estate.
  2. 26 USC §2037 - Transfers taking effect at death.
  3. 26 USC §2038 - Revocable transfers.
  4. 26 USC §2042 - Proceeds of life insurance.

A gift made beyond three years of the date of death, or that does not meet one of the four IRC provisions listed above, is not included in the Washington gross estate.

Does property (for example: real estate, IRAs, etc) need to be reported on an Estate Tax return if there is a “Transfer on Death” (TOD) designation?

Yes. Although property may be distributed directly to a surviving beneficiary after the decedent’s death, the property is considered an asset of the decedent on the date of death and must be included on the Estate Tax return.

Payment of estate taxes on TOD property is determined by RCW 83.110A.

Are there any special elections or deductions available when filing an estate tax return?

Is there an election for qualified terminable interest property (QTIP)?

Yes. For details, see the Estate tax qualified terminable interest property page.

Is there a farm deduction, if so, how much can be deducted?

The value of farm property (land, stock, produce, equipment, etc.) can be deducted from the taxable value of an estate as long as the value of farm property comprises at least half of the total adjusted value of the estate, and it meets other statutory requirements. The farm deduction is unlimited and is in addition to the applicable exclusion amount.

A tenant farmer may qualify for the farm deduction if certain requirements are met.

The definition of a farm includes stock, dairy, poultry, fruit, furbearing animals, and truck farms; plantation; ranches; nurseries; ranges; greenhouses or other similar structures used primarily for the raising of agricultural or horticultural commodities; and orchards and woodlands.

For more details, including the requirements for the farm deduction, see the Estate tax deduction for farms page.

Is there a deduction for family-owned business interests?

Yes, there is a deduction for qualified family-owned business interests (QFOBI). The QFOBI must meet certain requirements in order to be deducted from the estate.

The heirs of the QFOBI must continue the operation of the trade or business for three years after the decedent's death. If the heirs do not continue operation of the trade or business, additional tax will be due.

For more details, including the requirements for the QFOBI deduction, see the Estate tax qualified family-wwned business interests deduction page.

Am I allowed to defer estate taxes owed?

A portion of estate taxes owing may be deferred, but only on the part attributable to a qualified closely-held business.
 
The ability to defer the estate taxes attributable to a closely-held business is done by electing an installment plan consistent with §6166 of the Internal Revenue Code.

For more details, including the qualifications, see the Estate tax installment plans for closely-held businesses page.

Does Washington recognize portability of any unused exemption amount?

Washington law does not have, nor does it incorporate, the federal provisions of portability for estate tax. Each estate is entitled to the applicable exclusion amount based on the decedent’s date of death.

What expenses and/or deductions are commonly allowed on Schedules J, K, or L?
  • Funeral expenses (or half if community property estate).
  • Costs of administering the estate such as executor’s commissions, attorney fees, and accountant fees.
  • Appraisal fees for real estate, tangible personal property, jewelry, art, or other collections.
  • Outstanding property taxes (prorated up to the date of death only).
  • Debts of the decedent such as outstanding mortgages, credit cards, or similar debts (including interest accrued up to the date of death).
  • Expenses incurred from administering a trust.

Other miscellaneous questions

How do I leave a voice message for an estate tax examiner to call me back?

Call 360-704-5906, enter option 2 at the prompt, and then leave your voice message.

Please be sure to hit # after recording your message, in order to save and send your message. Failure to do so will prevent your message from being sent. We aim to return calls within two business days.

Is an electronic signature allowed?

We allow electronic signatures for estate tax documents. An electronic signature has the same effect as a written signature.

Below are some methods for creating electronic signatures:

  • Personal Identification Number (PIN) or password: When using a PIN or password for an e-signature, a person is required to enter identifying information, which may include an identification number, the person’s name and a “shared secret” such as a PIN and/or password. The system checks that the PIN and/or password is in fact associated with the person accessing the system and “authenticates” the person.
  • Digitized Signature: A digitized signature is a graphical image of a handwritten signature. This approach may use specialized hardware or software for additional security.
  • Digital Signature: A “digital signature”, is created when the signer uses a private signing key to create a unique mark (called a “signed hash”) on an electronic document. The recipient of the document uses the signer’s public key to validate the authenticity of the private key and to verify that the document was not altered after signing.
Can a committed intimate relationship (CIR) or meretricious relationship report community property? Can they take a marital deduction or use the QTIP election?

Per RWC 26.16.030, community property in Washington state can only occur for a legally married or state registered domestic partnership couple. A marital deduction and qualified terminable interest property (QTIP) trust election are available to a spouse. A spouse is either, a legally married person from any state, or in Washington, a state registered domestic partner (Chapter 26.60 RCW).  

For a couple in a committed intimate relationship or meretricious relationship, no community property exists, no marital deduction may be made, and no QTIP may be elected.

Can I submit the 706 Account Transcripts instead of the Estate Tax Closing Document letter?

Yes. We accept the 706 Account Transcripts in place of the Estate Tax Closing Document letter. The transcripts must display a code of 421 with the “Closed examination of tax return” statement. If the Code 421 line is missing, then the IRS has not issued their final determination of the estate tax filing. We cannot issue our final release until the we have a clear proof that the IRS has issued their final determination.

Where do I mail the Notification of Appointment of a Personal Representative to the Department of Revenue?

Send this notification to the Bankruptcy Unit in the Compliance Division.

Mailing address:

Bankruptcy Unit, Compliance Division
Department of Revenue
2101 4th Ave, Suite 1400
Seattle, WA 98121

Who can sign a Statute of Limitations Waiver Agreement with the Department of Revenue?

Only the person responsible for filing the return can sign a Statute of Limitations Waiver Agreement (RCW 83.100.020).

The person required to file the federal return means any person required to file a return required by chapter 11 of the internal revenue code, such as the personal representative of an estate.

 

How long do I have to file or amend an estate tax return? What is the statute of limitations for making elections?

For an estate that has not filed a return, there is no statute of limitations. The estate tax return may be filed at any time.  

For an estate that has filed a return, an amended return can be filed at any time. The department has four years either from the close of four-year period after a timely filed first return’s due date (including granted extensions) or from the date of a late filed first return, to adjust the return filing. However, for an amended return filed after the four-year statute of limitation period, the department has one year to review and adjust or bill.   

Be aware, that if the executor distributes the assets prior to paying the estate tax, we have an additional three years to assess taxes, penalties, and interest beyond the initial four-year statute of limitations period.  

The statutory period for making elections is as follows:
 
•    Alternate valuation election (§2032) can be made on late filed return; but no later than 1 year after the due date including any granted extensions.
•    Installment payment plan election (§6166) must be made on a timely filed return; has to be filed by the due date including any granted extensions.
•    Qualified conservation easement exclusion election (§2031) must be made on a timely filed return; has to be filed by the due date including any granted extensions.
•    Qualified domestic trust (QDOT) election (§2056A) can be made on late filed return; but no later than 1 year after the due date including any granted extensions. 
•    Qualified terminable interest property (QTIP) election (§2056(b)(7)) can be made on a late-filed return; so long as it is the first return filed.
•    Special use valuation election (§2032A) must be made on a timely filed return; has to be filed by the due date including any granted extensions.

How long does an estate have to submit a request for a refund?

If the department receives an application for refund by a taxpayer within the statutory period for assessment of taxes, penalties or interest, the department will refund the amount of the overpayment together with interest (RCW 83.100.130). However, Section (3) states:

(3) Except as otherwise provided in subsection (4) of this section and RCW 83.100.090, no refund shall be made for taxes, penalties, or interest paid more than four years prior to the beginning of the calendar year in which the refund application is made, or an examination of records is complete.

The period to request a refund ends four years after the beginning of the calendar year in which the tax payment (estimated or actual) was made.

For example: A refund request for any taxes (estimated or actual) paid in 2019 must be submitted by December 31, 2023. This is true even if the payment was an estimated payment made in 2019 with a request for an extension prior to the submission of a return. The four year non-claim statute period starts on the date the payment is made, even if it is made prior to the submission of a return.

However, RCW 83.100.130(4) states:

(4) The execution of a written waiver under RCW 83.100.095 shall extend the time for making a refund if, prior to the expiration of the waiver period, an application for refund is made by the taxpayer or the department discovers a refund is due.

Therefore, if an estate executes a statute of limitations wavier, they can have additional time to request a refund. However, a waiver agreement must be fully executed by the end of the non-claim statute (December 31 of the corresponding year). A waiver agreement must also be signed off by the Department of Revenue to be fully executed.