If you have just opened a tax assessment from the Washington State Department of Revenue, you probably have two questions: how did this happen, and can I fight it?
The answer to the second question is yes. Washington gives every taxpayer the right to challenge an assessment through an administrative appeal called a Rule 100 petition. But that right comes with a short clock and a set of expectations that are not obvious from the outside.
This guide explains how the process works in plain language.
What Is a Rule 100 Petition?
A Rule 100 petition is a formal request asking the Washington Department of Revenue to review and correct a tax assessment. The name comes from the regulation that governs it, WAC 458-20-100.
When you file one, your case goes to the Department’s Administrative Review and Hearings Division (ARHD). A tax review officer — an attorney employed by the Department — reads your petition, reviews the audit file, and issues a written determination.
You can use a Rule 100 petition to challenge:
- A business and occupation (B&O) tax assessment
- A retail sales tax or use tax assessment
- A real estate excise tax (REET) assessment
- Penalties and interest
- A denied refund claim
- An adverse written ruling about your future tax obligations
The 30-Day Deadline Is the Most Important Thing on This Page
You have 30 days from the date of the Department’s action to file your petition.
If you need more time, you must request an extension in writing, within that same 30 days. Asking on day 35 does not work. There is no informal grace period, and missing the deadline can end your appeal before anyone looks at the merits.
If your paperwork is incomplete, the Department will usually tell you and give you a chance to fix it. That is a real protection — but it is a safety net, not a strategy.
If you have an assessment in hand, calendar the deadline today.
What Actually Happens in a Rule 100 Appeal
The process is designed to be informal and non-adversarial. There is no courtroom, no jury, and no cross-examination.
Here is the usual sequence:
- You file the petition, identifying each issue you dispute and explaining why.
- The Department acknowledges it and sends a scheduling letter with your hearing date and document deadlines.
- The Audit Division files a response defending its assessment.
- A hearing is held, usually by telephone.
- You may submit additional documents and written argument.
- The tax review officer issues a written determination.
One detail worth understanding: the tax review officer works for the Department. This is a departmental review, not an independent tribunal. That does not mean you cannot win — but it does mean arguments asking the reviewer to disregard the Department’s own rules will not succeed at this level.
What Actually Wins a Washington Tax Appeal
Here is the single most useful thing to know:
The Department credits documents. It does not credit explanations.
Appeals succeed when the taxpayer produces records created by someone else, at the time of the transaction, for a reason unrelated to the tax dispute. That means things like:
- Signed contracts and written agreements
- Vendor and customer invoices
- Bank and merchant processor statements
- Reseller permits and exemption certificates
- Independent appraisals
- Recorded documents and regulatory filings
What consistently fails:
- Statements about what you meant or intended, without supporting records
- Spreadsheets and summaries you prepared yourself
- Records you recreated after the fact
- Your memory of what a Department employee told you over the phone
- Arguments that the assessment is simply unfair, or that paying it would be a hardship
That last point surprises people. Financial hardship is expressly not a basis for cancelling an assessment or waiving penalties. It is a reason to ask the Compliance Division about a payment plan — a separate conversation entirely.
Four Mistakes That Sink Otherwise Good Appeals
1. Treating the petition as a placeholder. The rule specifically invites you to submit documents you did not give the auditor — including contracts and invoices that were requested and never produced. The petition stage is your best remaining opportunity to build the record. Many taxpayers waste it.
2. Making one big argument instead of several specific ones. Assessments are built issue by issue. Appeals that separate each disputed item, with its own facts and its own supporting documents, do better than appeals built on a single sweeping theory.
3. Producing documents that cannot be matched to the assessment. Handing over a stack of invoices is not enough if no one can tie them to the specific line items in dispute. The connection has to be made for the reviewer, not left for them to figure out.
4. Leaving out the bad facts. The reviewer has the audit file and can research further. Unfavorable facts will surface. It is far better to address them directly than to have them discovered.
Do You Need a Tax Attorney for a Rule 100 Petition?
You are not required to have one. Many taxpayers file on their own, particularly for smaller assessments.
That said, the process rewards preparation more than advocacy. The work that changes outcomes happens before filing — identifying which issues are genuinely winnable, locating the documents that support them, and organizing everything so it connects to the assessment. An experienced Washington tax attorney can also tell you candidly which parts of an assessment are worth fighting and which are not, which often saves more than it costs.
It is also worth knowing that Washington does not allow you to recover your attorney’s fees in a Rule 100 appeal, even if you win completely. That should factor into the decision for smaller disputes.
Frequently Asked Questions
How long do I have to appeal a Washington Department of Revenue assessment? Thirty days from the date of the Department’s action. An extension is possible, but you must request it in writing within those same 30 days.
Does filing a petition stop collection? Filing generally pauses collection activity while the review is pending, but interest continues to accrue on unpaid tax. Ask about your specific situation rather than assuming.
Do I have to attend a hearing? No. You can request an in-person hearing, a telephone hearing, or no hearing at all. Telephone hearings are standard and work well for most cases.
What if I lose? A determination is the Department’s final decision, but it is not the end of the road. You may request reconsideration within 30 days, appeal to the Board of Tax Appeals, or pay the tax and sue for a refund in Thurston County Superior Court.
Can I appeal only part of an assessment? Yes — and you often should. Partial relief is a common and realistic outcome.
Is the Department’s assessment presumed correct? Effectively, yes. The burden is on the taxpayer to show the assessment is wrong. That is why documentation matters so much.
This post does not constitute legal advice and does not create an attorney-client relationship; it is merely a general discussion of points of the law and may not be complete or up to date. Please contact our office for a consultation to discuss how tax laws may be relevant to your specific situation.