What Is a Tax Affidavit and When Do You Need One?

A tax affidavit is a sworn written statement, signed under penalty of perjury, that confirms tax-related facts for the IRS, a state or local tax agency, or another party who needs those facts in writing. You might sign one to prove you are not a foreign person when selling U.S. real estate, to report a fraudulent return filed under your Social Security number, to certify a sale price for a county transfer tax, or to complain about a tax preparer. The signature is not ceremonial. A false statement can trigger a civil fraud penalty equal to 75% of any resulting underpayment and, in the worst cases, a federal felony carrying up to three years in prison.¹²

When You Actually Need One

Most people never see a tax affidavit unless a specific transaction or problem forces one into their lap. The common thread across these situations is that someone with authority needs you to put a tax-relevant fact in writing and stake your legal credibility on it.

Selling Real Estate

Nearly every property sale involves at least one tax affidavit. Many states and counties require a real estate transfer tax affidavit (sometimes called an excise tax affidavit) that reports the sale price, the type of property, and any exemption you’re claiming. The county uses it to calculate the transfer tax before recording the deed, and the exemption can be audited afterward.³ Your title company or closing attorney usually hands you the form; you’re the one swearing to what’s on it.

FIRPTA and Non-Foreign Status

When a foreign person sells U.S. real property, the buyer is generally required to withhold 15% of the sale price and send it to the IRS.⁴ If you are a U.S. citizen or resident alien, you avoid that withholding by giving the buyer a non-foreign status affidavit, sometimes called a FIRPTA certificate or transferor’s certification. The affidavit must include your name, U.S. taxpayer identification number, and home address, and you sign it under penalties of perjury. The certification is void if the buyer has actual knowledge that it is false.⁵ For homes purchased as a residence with a sale price under $1,000,000, the withholding rate drops to 10% rather than 15%.

Skip the affidavit and the buyer withholds tens of thousands of dollars from your proceeds at closing. A false one can leave the buyer on the hook for the 15% they thought they didn’t have to withhold, which tends to generate lawsuits.⁶

Reporting Identity Theft

If someone uses your Social Security number to file a fraudulent return, you report it to the IRS on Form 14039, the Identity Theft Affidavit.⁷ The usual triggers are an e-file rejection because a return was already submitted under your SSN, a notice about wages from an employer you never worked for, or a tax transcript you didn’t request.⁸ You can submit the form online, print and mail it, fax it, or route it through the Federal Trade Commission, which forwards it to the IRS. Don’t send duplicates while waiting; it slows the case down.⁹

Reporting a Bad Tax Preparer

If a preparer altered your return, filed it without your consent, or otherwise misbehaved, the IRS investigates through Form 14157-A, the Tax Return Preparer Fraud or Misconduct Affidavit.¹⁰ You sign it under penalties of perjury, declaring that what you’re saying about the preparer is true, correct, and complete.¹¹

Settling a Small Estate

When someone dies with a small estate, most states let heirs skip formal probate by filing a small estate affidavit. The affiant usually has to declare under oath that the deceased’s debts and taxes have been paid before any remaining assets are distributed. Thresholds and requirements vary widely; check your state’s probate code before assuming you qualify. Federal estate tax filings use Form 706 rather than an affidavit, though state-level inheritance taxes sometimes involve sworn statements of their own.

Do You Need a Notary?

Not usually, if the affidavit is a federal tax form. Under federal tax law, returns, declarations, and statements are verified by a written declaration made under penalties of perjury, not by notarization.¹³ That’s why Form 14039, Form 14157-A, and most other IRS forms print “under penalties of perjury” above the signature line and don’t include a notary block.

State and local affidavits are a different story. A real estate transfer tax affidavit filed with a county recorder almost always needs notarization, as does a small estate affidavit filed in probate. A notary performing a jurat (the notarial act used for affidavits) confirms that the signer appeared in person, was properly identified, and swore to the document’s truthfulness before signing.¹⁴

Practical rule: check the form. If it has a notary block, find a notary. Banks, credit unions, UPS stores, and some public libraries offer the service. If it says “under penalties of perjury” with only a signature line, your signature alone creates the legal obligation.

What Goes on the Form

The specifics vary, but most tax affidavits share the same bones:

Identifying information: full legal name, address, Social Security number or taxpayer identification number, sometimes a phone or email.
The facts you’re swearing to: a sale price, your citizenship or residency status, a description of identity theft, the value of donated property, or whatever else the form targets.
A perjury declaration stating that the information is true, correct, and complete. On IRS forms, this language is standardized.
Your signature and date. On state and local forms, a notary block follows.

Some affidavits demand supporting documentation. Form 14039 asks for a copy of a government-issued ID. Form 8283 requires a qualified appraisal for high-value property donations. The form’s instructions will spell out what to attach.

Preparing and Filing

Start with the current version of the correct form. For IRS affidavits, download from irs.gov; an outdated form can cause rejections. For real estate transfer tax affidavits, the county recorder, title company, or closing attorney will provide the version your jurisdiction accepts. Using the wrong one can lead to incorrect tax calculations and rejection at recording.¹⁵

Gather your records first: financial statements, deeds, identification, prior returns, whatever the affidavit asks about. Errors on a sworn statement are disproportionately painful to fix.

Review the completed form. Then either sign it (for IRS forms with a perjury declaration) or take it to a notary (for state and local forms with a notary block). File it with whoever required it, using the address or method in the form’s instructions. Real estate affidavits typically go to the county as part of the deed recording package.

Keep a copy. The IRS recommends retaining tax records for at least three years after filing, longer in some situations. Claims for worthless securities or bad debt: seven years. Failure to report more than 25% of gross income: six years. Never filed, or filed fraudulently: indefinitely.¹⁶

What Happens if You Lie

Anyone who willfully makes a false statement on a document signed under penalties of perjury in connection with a tax matter commits a felony. The maximum punishment is a fine of up to $100,000 ($500,000 for a corporation) and up to three years in prison.¹ Prosecutors do not need to prove the false statement caused a specific tax loss; signing the false sworn document is itself the crime.

On the civil side, if a false statement causes an underpayment, the IRS can impose a fraud penalty equal to 75% of the portion of the underpayment attributable to fraud.² That stacks on top of the tax owed, plus interest. The IRS has to prove fraud by clear and convincing evidence, but once it meets that bar, the math gets ugly quickly. Those penalties are exactly why the sworn statement carries weight in the first place.

1
Office of the Law Revision Counsel. 26 USC 7206 – Fraud and False Statements
2
Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty
3
Washington Department of Revenue. Real Estate Excise Tax Exemptions (Commonly Used)
4
Office of the Law Revision Counsel. 26 USC 1445 – Withholding of Tax on Dispositions of United States Real Property Interests
5
Internal Revenue Service. Exceptions from FIRPTA Withholding
6
Internal Revenue Service. FIRPTA Withholding
7
Internal Revenue Service. Form 14039 – Identity Theft Affidavit
8
Internal Revenue Service. When to File an Identity Theft Affidavit
9
Internal Revenue Service. How IRS ID Theft Victim Assistance Works
10
Internal Revenue Service. Form 14157-A – Tax Return Preparer Fraud or Misconduct Affidavit
11
Internal Revenue Service. Form 8283 – Noncash Charitable Contributions
13
Office of the Law Revision Counsel. 26 USC 6065 – Verification of Returns
14
American Society of Notaries. Your Basic Duties As a Notary Public
15
Washington Department of Revenue. Real Estate Excise Tax Forms
16
Internal Revenue Service. How Long Should I Keep Records