If you file your returns electronically, you can also amend your returns online in My DOR. Options for electronic payments are available.
Schedule of amended figures
If you need to amend multiple periods (e.g. a year or more), an alternative to filing individual returns is to submit a schedule of amended figures. To properly prepare a schedule, show all figures as they should have been reported on the original returns. The schedule must provide the Department with sufficient information to compute the differences in income, deductions, local taxes and any penalties for as many return periods as needed.
When submitting a schedule of amended figures please remember to:
List the tax account ID for the business on all pages of the schedule.
Clearly indicate which periods are being amended.
Report all information using the same frequency as that on your original tax return (unless instructed otherwise).
Calculate tax using rates shown on your original return. Please include the rates on your schedule.
Include a complete explanation for adjustments.
Schedules can be sent electronically using the Send a Message option in My DOR on the More Options tab, or mailing them to the address listed in step 7 below under By paper.
Making Payment: Payments for additional taxes due can be made through My DOR using the Make a Payment option.
However, if you have been granted a waiver from the mandatory e-file/e-pay requirement, you may mail a check with your scheduled amended figures.
Make a copy of the return you need to correct.
Check the box related to “Filing an Amended Return” located on page one.
Draw a single line through any incorrect information and write the correct information to the side or above. (Please use black ink only.)
Recalculate your "Totals."
Attach a short letter explaining what you are changing and why. If you are expecting a refund, please indicate if you prefer a refund or credit.
If you are amending your return and you owe money, include a check when you mail the amended return.
Mail the amended return to:
Washington State Department of Revenue
Taxpayer Account Administration
PO Box 47476
Olympia, WA 98504-7476
The department will review the amended returns you file. In addition, the following penalties may apply to underreported amounts:
Late payment return penalties up to 29% if you originally filed no business or zero returns, were on active non-reporting status, or your original returns were filed late.
5% assessment penalty for substantially underpaid tax if the underreported tax is underpaid by at least 20%. WAC 458-20-228
Note: The department may only honor refunds dating back four years prior to the year in which the refund request is made. WAC 458-20-229
Amend a return originally filed with no business
If you file a tax return reporting no business activity and later discover that you did have business activity to report for that period, you should amend that return. Do not adjust a later return for the additional revenue to report. If you amend to report activity on a return that was previously reported with no activity, penalties will apply.