UN Income Tax Forms: Filing Requirements, Deadlines, and Form F.65

If you are a US citizen or lawful permanent resident on the UN payroll, the UN income tax forms you file each year are Form F.65 (Request for Income Tax Settlement and Income Tax Advances), Form F.65/A when the Income Tax Unit asks for it, IRS Form 4506-C, and signed copies of your completed federal, state, and local returns. For the 2025 tax year, US-based staff must get the full package to the Income Tax Unit by March 3, 2026; staff working outside the US have until April 1, 2026.¹ Both dates fall before the IRS filing deadline, and that gap is where most staff run into trouble.

Who Has to File These Forms

US citizens and green card holders owe federal income tax on their worldwide income, including UN salary,² and that liability is what the UN reimburses. If you fall into either group, you file Form F.65 with the Income Tax Unit every year.

Most non-US staff on G-4 visas do not file UN tax forms at all. The IRS treats full-time employees of international organizations holding G-class visas as foreign government-related individuals whose days in the US do not count toward the substantial presence test,³ and their UN salary is exempt from US tax. A G-4 holder’s spouse or dependent who takes outside employment in the US is a separate matter and is not covered by that exemption.

The Forms in a Complete Submission

A complete filing brings together UN paperwork and IRS paperwork in one package:

Form F.65, the main UN form, which covers both your prior-year settlement and your current-year advance request in a single document. The current version is coded F.65 (1-26).⁴
Form F.65/A, a supplement the Tax Unit may require to support your settlement figures depending on your situation.⁵
IRS Form 4506-C, an authorization that lets the IRS release your return information to the Income Tax Unit through the Income Verification Express Service so the unit can confirm your submitted figures.⁶
A signed copy of your IRS Form 1040 with all schedules.
Signed copies of any state and local income tax returns you filed.

All UN-specific forms are posted by the Income Tax Unit.⁵ You can submit through the Tax Unit’s secure upload portal or by registered mail to the New York office.

Filing Deadlines for 2026

The UN’s internal cutoffs run ahead of the IRS calendar. For the 2025 tax year settlement and the 2026 advance request:

Staff working in the US: complete, signed submission to the Income Tax Unit by March 3, 2026.
Staff working outside the US: submission by April 1, 2026. These staff also get an automatic two-month IRS filing extension to June 15, 2026.
IRS federal filing and payment deadline: April 15, 2026 for all filers.¹

The practical consequence: US-based staff have to finish their federal and state returns roughly six weeks before the IRS wants them. If the returns are not done by early March, the UN deadline passes even though the IRS has not started charging anything.

How Form F.65 Works

Form F.65 does two jobs. The settlement section looks backward at the tax year you just closed: the Tax Unit compares what you actually owed against the advances the UN already paid and either issues a balancing payment or recovers an overpayment. The advance section looks forward: it authorizes the UN to make quarterly estimated tax payments for the current year on your behalf.¹

The form asks for your UN index number, Social Security number, visa status since January 1 of the prior tax year, official duty station, whether you telecommute, and the names and Social Security numbers of your dependents.⁴ The settlement figures come directly off your completed 1040 and state returns, so finish those first. Numbers on the F.65 have to match the returns exactly; mismatches are one of the most common causes of processing delays.

If you want the UN to handle your current-year estimated payments, complete the advance section. Leave it blank and you are on your own for quarterly payments, and the form warns that any resulting underpayment penalties are yours to absorb.⁴

Signing the F.65 commits you to several certifications: that your returns are true and complete, that you will forward any advance checks made out to a tax authority promptly rather than deposit them, and that you will notify the Income Tax Unit within 30 days if you file an amended return or your tax liability changes for any reason.⁴

How Advance Payments Flow

Because the UN has no payroll withholding, someone has to make quarterly estimated payments to the IRS and state authorities. Once you request advances on the F.65, the Income Tax Unit deposits federal payments into your IRS account through the Electronic Federal Tax Payment System and pays New York State on your behalf.⁷

For staff based in Washington, D.C., Virginia, or Maryland, state advances work differently. The UN sends the money to you, and you forward it to the state tax authority yourself.⁷ If a check is earmarked for a tax authority, the F.65 certification requires you to transmit it promptly and not deposit it into a personal account.

Eligibility for advances requires a UN contract of at least six months. Staff on “when actually employed” (WAE) contracts do not qualify.¹ New or newly eligible staff start the advance process by submitting Form F.65.

Self-Employment Tax Is Your Responsibility Too

Employees of international organizations are exempt from FICA withholding on wages for services performed in their official capacity.⁸ For US citizens and permanent residents that exemption is not the end of the story: federal law makes you liable for self-employment tax on UN income earned for services performed in the United States. The total rate is 15.3 percent, made up of 12.4 percent for Social Security and 2.9 percent for Medicare, reported on Schedule SE with your Form 1040.⁹ Earnings for services performed outside the US are generally exempt.

The UN reimburses roughly the employer’s half, the 7.65 percent that a private-sector employer would pay if you had a normal payroll relationship, and its advance calculations include self-employment tax when it makes your quarterly estimated payments.¹ Paying self-employment tax is also how you build Social Security and Medicare credits that stay with you if you leave the UN.

State and Local Returns

UN reimbursement covers state and local income taxes on your UN salary, not just federal.⁷ Include signed copies of every state and local return you filed in your submission package so the Income Tax Unit can settle the full amount. Where you live determines whether the UN pays the state directly (New York) or hands you the money to forward (DC, Maryland, Virginia).

What Happens If You Miss the UN Deadline

A late submission to the Income Tax Unit sets off a sequence of consequences that reaches beyond a delayed reimbursement check. According to the 2026 tax briefing:

The UN will not reimburse penalties or interest imposed by tax authorities because of a late filing, under any circumstances.
Your 2026 advance payments will be held up, which can cause you to miss IRS quarterly deadlines and rack up underpayment penalties you pay yourself.
If your tax claim is still not submitted by October 15, 2026, the UN will recover any 2025 advances it already paid on your behalf by deducting from your salary.¹

The UN will pick up interest or penalties in only a few narrow cases: when the delay was the UN’s own fault, for overseas staff up to the June 15 extended deadline, or when advances fell short because your contract was too short to qualify.¹ Outside those exceptions, every penalty dollar is yours. Finishing your returns in time to meet the March 3 UN cutoff is the single most useful thing US-based staff can do to keep the reimbursement running on schedule.

1
United Nations Income Tax Unit. 2026 Income Tax Reimbursement Procedures
2
Internal Revenue Service. Tax Information and Responsibilities for New Immigrants to the United States
3
Internal Revenue Service. Exempt Individuals: Foreign Government-Related Individuals
4
United Nations. Request for 2025 Income Tax Settlement and 2026 Income Tax Advances
5
United Nations Income Tax Unit. UN Forms and Publications
6
Internal Revenue Service. Income Verification Express Service (IVES)
7
United Nations Income Tax Unit. Frequently Asked Questions
8
Internal Revenue Service. Aliens Employed in the U.S. – Social Security Taxes
9
Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)