IRS country codes are two-letter identifiers that U.S. taxpayers and withholding agents must use to report foreign income, assets, accounts, and entities on federal tax forms. The official list sits at IRS.gov/CountryCodes and covers more than 250 countries, territories, and special designations.1Internal Revenue Service. Country Codes The list loosely tracks the ISO 3166-1 alpha-2 standard used by most international organizations, but it diverges in dozens of places, and those differences are the reason copying a code from a non-IRS source is one of the fastest ways to get a return rejected.
Where the Official List Lives
The only authoritative source is the IRS’s own page at IRS.gov/CountryCodes. Every form that asks for a country code — Form 1116, Form 1042-S, Form 5471, and the rest — points back to that page in its instructions.1Internal Revenue Service. Country Codes The page was last updated in September 2025, and the IRS revises it periodically as countries change names, merge, or gain independence. The page shows its last review date, so a quick glance tells you whether anything has moved since you last filed.
How the Codes Work
Every IRS country code is exactly two capital letters. Canada is CA, Mexico is MX, Japan is JA. The e-file system validates each code against the official list. A three-letter code, a lowercase code, or a two-letter code that isn’t on the IRS list will trigger a rejection before the return reaches a human reviewer.1Internal Revenue Service. Country Codes
When the country you need to report isn’t on the list, you enter OC for Other Country. On Form 1042-S, the instructions say to use OC “only when the country of residence does not appear on the list.”2Internal Revenue Service. Country Codes for Form 1042-S Reserve it for cases where you’ve confirmed the country genuinely isn’t listed, not as a workaround for a code you couldn’t find quickly.
Where IRS Codes Differ From ISO
This is where most filing errors happen. The IRS deviates from the ISO 3166-1 alpha-2 standard for a surprising number of countries that American taxpayers deal with regularly. Some of the notable mismatches:
- United Kingdom: IRS uses UK; ISO uses GB
- Switzerland: IRS uses SZ; ISO uses CH
- South Korea: IRS uses KS; ISO uses KR
- Czech Republic: IRS uses EZ; ISO uses CZ
- Ivory Coast (Côte d’Ivoire): IRS uses IV; ISO uses CI
- Eswatini (Swaziland): IRS uses WZ; ISO uses SZ
Notice the Eswatini/Switzerland overlap. The ISO code for Eswatini (SZ) is the IRS code for Switzerland. A taxpayer reporting Swiss bank account income who reaches for the ISO standard would accidentally tag the return as Eswatini. The e-file system wouldn’t reject the entry, because SZ is a valid IRS code. It would just associate the income with the wrong country, which can create issues with treaty benefits or audit flags later.1Internal Revenue Service. Country Codes
U.S. Territories and the “US” Code
U.S. territories have their own two-letter codes, separate from US. The common ones:
- American Samoa: AQ (ISO uses AS)
- Guam: GQ (ISO uses GU)
- Puerto Rico: RQ (ISO uses PR)
- U.S. Virgin Islands: VQ (ISO uses VI)
Every one of these differs from the ISO standard.1Internal Revenue Service. Country Codes
In November 2024, the IRS added US as a reportable country code for the first time. Previously no form accepted it, because the codes were designed exclusively for foreign jurisdictions. The change applies to Form 926, Form 1118, Form 3520, and Form 8805, where certain reporting scenarios now require identifying the United States itself.1Internal Revenue Service. Country Codes Don’t enter US on other forms. It will still trigger a rejection everywhere it isn’t specifically authorized.
Which Forms Require a Country Code
Country codes appear across a wide range of IRS and FinCEN forms.
Form 1116 — Foreign Tax Credit
Individual taxpayers claiming a credit for income taxes paid to a foreign government report each country in a separate column in Part I of Form 1116, identified by its two-letter code.3Internal Revenue Service. Instructions for Form 1116 The accompanying Schedule C also requires country codes on lines referencing tax payments and directs filers to IRS.gov/CountryCodes.4Internal Revenue Service. Instructions for Schedule C (Form 1116)
Form 2555 — Foreign Earned Income Exclusion
Taxpayers claiming the foreign earned income exclusion must identify their foreign country of residence or physical presence on Form 2555, tied to the bona fide residence test or physical presence test.5Internal Revenue Service. 2025 Instructions for Form 2555 – Foreign Earned Income
Form 1042-S — Foreign Person’s U.S. Source Income
Withholding agents enter the recipient’s country of tax residency in Box 13b using the IRS two-letter code. The field carries extra weight when treaty benefits are involved. If the form claims reduced or exempt withholding under a tax treaty (exemption code 04 in Box 3a, or a reduced rate in Box 3b), the country code in Box 13b must correspond to a country that actually has a treaty with the United States. A non-treaty country paired with a treaty claim creates a mismatch the IRS flags.6Internal Revenue Service. Instructions for Form 1042-S (2026)
FinCEN Form 114 — FBAR
The Report of Foreign Bank and Financial Accounts requires a country code for every foreign financial account being reported.7Internal Revenue Service. FinCEN Form 114 – Report of Foreign Bank and Financial Accounts (FBAR) The country that matters here is where the account is located, not where the financial institution is headquartered. The FBAR is filed through FinCEN’s BSA E-Filing system, separately from your tax return.8Internal Revenue Service. Report of Foreign Bank and Financial Accounts (FBAR)
Form 8938 — Specified Foreign Financial Assets
Form 8938 reports specified foreign financial assets under FATCA and uses the two-letter codes to identify jurisdictions.9Internal Revenue Service. Do I Need to File Form 8938, Statement of Specified Foreign Financial Assets
Forms for Foreign Entities
Several forms aimed at U.S. persons with interests in foreign businesses call for country codes in specific fields. Form 5471 requires them on Schedule E for taxes paid to foreign countries and on Schedule Q for sanctioned-country reporting.10Internal Revenue Service. Instructions for Form 5471 Form 8865 requires the two-letter code for the country of organization of any foreign partner that is not an individual.11Internal Revenue Service. 2025 Instructions for Form 8865 Form 926 requires the code for the transferee corporation’s country of incorporation.12Internal Revenue Service. Instructions for Form 926 Form 3520 uses codes to identify a foreign trust’s jurisdiction.13Internal Revenue Service. Instructions for Form 3520
What Happens When You Get One Wrong
An incorrect country code rarely produces a headline-grabbing penalty on its own, but it can cascade. On an electronically filed return, a bad code typically triggers an outright rejection, which means the return isn’t considered filed until you correct and resubmit. If that correction pushes you past a filing deadline, late-filing penalties start accruing on top of anything else you owe.
Information returns are a different story. For returns like Form 1042-S, IRC Section 6721 imposes penalties for filing with incorrect information. For returns due in 2026, the penalty is $340 per return, capped at $4,098,500 annually for larger businesses and $1,366,000 for businesses with average gross receipts of $5 million or less. Catching the error early lowers the number: correcting within 30 days of the filing deadline drops the per-return penalty to $60, and correcting before August 1 drops it to $130.14Internal Revenue Service. Revenue Procedure 2024-40 Intentional disregard of the filing requirements pushes the penalty to $680 per return with no annual cap.15Office of the Law Revision Counsel. 26 U.S. Code 6721
Form 8938 has its own structure. Failing to file a complete and correct form can result in a $10,000 penalty, with an additional $10,000 for each 30-day period of continued noncompliance after IRS notice, up to $50,000 more. Understating tax because of an undisclosed foreign asset can trigger an accuracy-related penalty of 40% of the underpayment.16Internal Revenue Service. Instructions for Form 8938
The practical concern with a wrong code on something like Form 1042-S isn’t only data quality. It can also undermine treaty claims. A treaty-reduced withholding rate paired with a non-treaty country code may prompt the IRS to treat the withholding as insufficient and assess additional tax against the recipient.
Keeping the List Current
The IRS updates the country code list without a fixed schedule. Changes reflect geopolitical events — new countries, name changes, territorial reorganizations — and administrative decisions like the 2024 addition of the US code. Official guidance is announced through the Internal Revenue Bulletin, published weekly.17Internal Revenue Service. Internal Revenue Bulletins The more reliable habit is simply checking IRS.gov/CountryCodes before filing any form that requires a country identification. If you file internationally on a recurring basis, bookmarking that page and looking at it at the start of each filing season takes about 30 seconds and eliminates the most common source of preventable rejections.