The Mobile Home Real Estate Excise Tax Affidavit (form REV 84 0003e) is the affidavit that seller and buyer sign when title to a mobile home is transferred; it is submitted to the County Treasurer of the county where the property is located. Thurston County lists it among the Treasurer's online forms, and it touches Thurston County property tax because its Treasurer's Certificate confirms that property taxes on the mobile home have been paid. On this page you can fill out the form online on FillingPDF and download or print the completed PDF; the form itself is published by the county at thurstoncountywa.gov.
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What is REV 84 0003e?
The Mobile Home Real Estate Excise Tax Affidavit is the form, prepared under Chapter 82.45 RCW and Chapter 458-61A WAC, that you complete when transferring title to a mobile home only. Once the cashier stamps it, it is your receipt.
The printed form says it is used for sales on or after May 1, 2026, and carries the code REV 84 0003e (3/11/26). It is a single affidavit printed in five copies, each marked for a different recipient: County Treasurer, County Assessor, Dept. of Revenue, County Auditor/Licensing Agent and Taxpayer.
The instructions explain when a used mobile home counts as real estate. It must have been previously taxed through retail sales tax or use tax, and it must have substantially lost its identity as a mobile unit by being fixed on land owned or leased by its owner, placed on a foundation (posts and blocks) and connected to sewer, water and other utilities. Transfers that meet this test are subject to the real estate excise tax; the instructions list other transfers, such as those where the written agreement requires the unit to be moved, as subject to retail sales or use tax instead.
The form also gathers the figures the county needs: sale price, state and local excise tax, any delinquent interest and penalty, the State Technology Fee and the Affidavit Processing Fee. Thurston County lists it with its other real estate excise tax forms, including the Single Location and Multiple Location Real Estate Excise Tax Affidavits.
Who needs to file REV 84 0003e?
The seller and the buyer in a transfer of title to a mobile home complete and sign this affidavit; an agent may sign for either. It is built for transfers of a mobile home only, not for land sales.
Under the instructions, a used mobile home transfer is subject to the real estate excise tax in these cases:
- transfers between individuals, with no requirement that the unit be moved;
- a trade-in from an individual to a dealer, with no requirement that the unit be moved;
- a transfer from a dealer to an individual, with no requirement that the unit be moved. A dealer may be allowed credit on the excise tax if the unit was taken in trade, was not moved and was resold within nine months.
When a transfer is subject to the excise tax, the liability is the seller's. When the transfer is subject to retail sales or use tax, such as a transfer between individuals where the written agreement requires the unit to be moved, or any transfer from a dealer's sales lot, the liability is the purchaser's or user's.
The form lists a Legal Owner block, and a buyer, seller or agent who claims an exemption must write the exemption number and title on the form.
When to file REV 84 0003e
The tax is due at the time of the sale or transfer, so the affidavit is prepared when title to the mobile home changes hands. If the tax is not paid within one month of the date of sale or transfer, interest and delinquent penalties apply. The interest rate is variable, and the penalties increase at one, two and three months after the due date. This edition is for sales on or after May 1, 2026.
The form has no renewal or validity period. After filing, keep the documentation that supports the selling price or any exemption you claimed for at least four years from the date of sale, because the information on the affidavit is subject to audit by the Department of Revenue.
Documents you need
- A copy of the Treasurer's Certificate stating that property taxes on the mobile home have been paid; the instructions say it is used together with a copy of the affidavit as evidence of payment of taxes.
- The completed predominate use calculator, only if the property is used predominantly for timber or agriculture and the transfer involves multiple parcels with different classifications.
- Documentation supporting the selling price or any exemption claimed; keep it for at least four years from the date of sale and provide it if the Department of Revenue audits the affidavit.
How to fill out REV 84 0003e
Enter the seller's details
In the Registered Owner (Seller) block, type or print the name, street, city, state, zip code and phone number. Complete every area, since incomplete affidavits can be rejected.
Enter the buyer's details
In the New Registered Owner (Buyer) block, give the name, street, city, state, zip code and phone number.
Add the legal owner
In the Legal Owner block, enter the name and street, city, state and zip code of the legal owner of the mobile home.
Give the location and parcel numbers
Under Location of Mobile Home, enter the street, city, state and zip code. Enter the Parcel or Account No. and the assessed value(s) under both Personal Property and Real Property.
Describe the mobile home
Enter the Make, Year, Model, Size and Serial No. or I.D., and the Revenue Tax Code No.
Answer the timber or agriculture question
Mark Yes or No for whether the property is predominantly used for timber or agriculture and will continue in its current use. If Yes and multiple parcels have different classifications, complete the predominate use calculator.
Enter the date and sale price
Enter the Date of Sale and the Taxable Sale Price. Use the Select Location field for the local excise tax.
Complete the tax and fee lines
Fill in Excise Tax (State and Local), Delinquent Interest and Delinquent Penalty if the sale is late, the State Technology Fee and Affidavit Processing Fee, then Subtotal and Total Due. Check the county's current amounts with the County Treasurer.
List any exemption
If an exemption is claimed, write the Exemption No. (Sec/Sub) and the Exemption Title.
Sign and date the affidavit
Seller/Agent and Buyer/Agent each sign, print a name and enter the date and place of signing under the penalty of perjury statement.
Leave the Treasurer's block blank
The Treasurer's Certificate and the area marked Treasurer's use only are completed by the County Treasurer or a deputy.
Review and download the completed PDF
Check the names, parcel numbers, date of sale and signatures on all copies, then download or print the completed PDF from FillingPDF and take it to the County Treasurer as described under How to submit.
How to submit REV 84 0003e
Submit the completed affidavit to the County Treasurer, or the Treasurer's or Record's Office, of the county where the mobile home is located.
- In person at the county office: the form says the cashier stamps it, and the stamped affidavit is your receipt. Thurston County publishes the form on its Treasurer's online forms page at https://www.thurstoncountywa.gov/departments/treasurer/online-forms.
- Treasurer's Certificate: the County Treasurer or a deputy completes the certificate that property taxes on the mobile home are paid; the block is marked "Treasurer's use only." The instructions say a copy of the affidavit and a copy of this certificate are evidence that taxes were paid, and the Department of Licensing cannot transfer or issue a certificate of ownership until it has verified that the excise, sales or use tax and any property taxes due have been paid.
- Payment: tax and the fees printed on the form, the State Technology Fee and the Affidavit Processing Fee, are due with the affidavit. The form states a minimum is due in fees and/or tax; ask the County Treasurer for current amounts and accepted payment methods.
The form names no mailing address or online filing channel. To request the form in an alternate format, call 360-705-6705; TTY users can use Washington Relay Service at 711. FillingPDF lets you fill out and download the PDF; submission follows the channels above.
Common mistakes to avoid
- Leaving areas blank or inaccurate: the form says it will not be accepted unless all areas are fully and accurately completed, and the county may reject it.
- Using the affidavit for something other than a title transfer of a mobile home; the form is marked for that use only.
- Using this edition for a sale dated before May 1, 2026; the printed form is for sales on or after that date.
- Paying later than one month after the sale or transfer, which triggers interest and delinquent penalties.
- Submitting it to a county where the mobile home is not located; the form goes to the Treasurer of the county in which the property is located.
- Selling a mobile home with a tax lien and not telling the buyer; the form warns this is deliberate deception, treated as Fraud and/or Theft under Title 9 and 9A RCW.
- Claiming an exemption without writing the exemption number (Sec/Sub) and exemption title in the space provided.
- Throwing away records after filing; support for the price or an exemption must be kept at least four years from the date of sale.
Frequently asked questions
What is the Mobile Home Real Estate Excise Tax Affidavit?
It is the affidavit (REV 84 0003e) completed when title to a mobile home is transferred. It reports the sale and the real estate excise tax under Chapter 82.45 RCW, and the cashier-stamped copy is your receipt.
Does this form relate to Thurston County property tax?
Partly. The form is an excise tax affidavit, but it includes a Treasurer's Certificate that property taxes on the mobile home have been paid. The Department of Licensing will not transfer or issue a certificate of ownership until property taxes due are verified as paid.
Who is responsible for the excise tax on a mobile home sale?
The seller. The instructions say that if the transfer is subject to the real estate excise tax, it is the seller's liability; if it is subject to retail sales or use tax, it is the purchaser's or user's liability.
Where do I submit the mobile home excise tax affidavit?
Submit it to the County Treasurer's or Record's Office in the county where the mobile home is located. The form names no mailing address, so contact that office for hours and accepted payment methods.
When is the tax due and what happens if I am late?
The tax is due at the time of the sale or transfer. If it is not paid within one month, interest and delinquent penalties apply, and the penalties increase at one, two and three months after the due date.
Are there fees in addition to the tax?
Yes. A State Technology Fee is due on all transactions, and an Affidavit Processing Fee applies where no tax is due or the tax is small. The form states a minimum is due in fees and/or tax; ask the County Treasurer for amounts.
How long should I keep records for the affidavit?
Keep the documentation supporting the selling price or any exemption for at least four years from the date of sale. The Department of Revenue can audit the information, and in an audit proving the price or exemption is the taxpayer's responsibility.
Can I fill out the mobile home excise tax affidavit online?
You can fill out the PDF online on FillingPDF and download or print it. FillingPDF is an independent service and does not file the affidavit; you submit it to the County Treasurer yourself.
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