Excluded expenses

There may be excluded from the measure of tax amounts representing money or credit received by a taxpayer as reimbursement of an advance in accordance with the regular and usual custom of his business or profession. The word “reimbursement” means money or credits received from a customer or client to repay the taxpayer for money or credits expended by the taxpayer in payment of costs or fees for the client. An excludable reimbursement applies only when the customer or client alone is liable for the payment of the fees or costs and when the taxpayer making the payment has no personal liability therefore, either primarily or secondarily, other than as agent for the customer or client.

References:
WAC 458-20-111