The IRS country codes are the two-letter identifiers U.S. taxpayers and withholding agents must use to name a foreign country on federal tax forms, and the only authoritative list sits at IRS.gov/CountryCodes.1Internal Revenue Service. Country Codes The list covers more than 250 countries, territories, and special designations, and it differs from the ISO 3166-1 alpha-2 codes used on shipping labels, passports, and most reference sites. That difference is why copying a code from any non-IRS source is one of the most common ways to get a return rejected.
Where the Official List Lives
IRS.gov/CountryCodes is the page referenced by the instructions for every form that asks for a country identifier, from Form 1116 to Form 1042-S to Form 5471.1Internal Revenue Service. Country Codes It was last updated in September 2025, and the IRS revises it as countries change names, merge, or gain independence. The page displays its last review date, so a quick glance tells you whether anything has moved since your last filing.
The IRS list loosely tracks the ISO 3166-1 alpha-2 standard, but the two diverge in dozens of places. Wikipedia, shipping software, and international banking systems all use ISO. The IRS does not.
How the Codes Are Formatted
Every code is exactly two capital letters. Canada is CA, Mexico is MX, Japan is JA. The e-file system checks each entry against the official list, so 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 reviewer.1Internal Revenue Service. Country Codes
When a country you need isn’t on the list, you enter OC for Other Country. On Form 1042-S, the instructions direct filers to use OC “only when the country of residence does not appear on the list.”2Internal Revenue Service. Country Codes for Form 1042-S Use it sparingly, and only after confirming the country genuinely isn’t listed under a different name.
IRS Codes That Differ From ISO
This is where most filing errors happen. Countries American taxpayers deal with regularly carry IRS codes that don’t match the ISO version:
- 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
Look closely at the last two. The ISO code for Eswatini is SZ, which is the IRS code for Switzerland. A taxpayer reporting a Swiss bank account who defaults to the ISO standard would tag the income as Eswatini. The e-file system wouldn’t reject the entry because SZ is a valid IRS code. It would simply attach the income to the wrong country, which can create issues with treaty benefits and audit flags later.1Internal Revenue Service. Country Codes
U.S. Territories and the New “US” Code
Every U.S. territory carries an IRS code that differs from its ISO counterpart:
- 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)
Same rule: use the IRS list.1Internal Revenue Service. Country Codes
In November 2024, the IRS added “US” as a reportable code for the first time. The codes had always been reserved for foreign jurisdictions. The change applies only to Form 926, Form 1118, Form 3520, and Form 8805, where specific reporting scenarios now call for identifying the United States itself. Entering “US” on any other form will still trigger a rejection.1Internal Revenue Service. Country Codes
Forms That Require a Country Code
Country codes appear on a wide range of IRS and FinCEN filings. If you’re filing any of the following, the code field is not optional.
Form 1116, Foreign Tax Credit
Individuals claiming a credit for income taxes paid to a foreign government enter a country code for each country in a separate column in Part I.3Internal Revenue Service. Instructions for Form 1116 Schedule C also requires country codes on lines referencing tax payments and points filers to IRS.gov/CountryCodes.4Internal Revenue Service. Instructions for Schedule C (Form 1116)
Form 2555, Foreign Earned Income Exclusion
Taxpayers who qualify under the bona fide residence or physical presence test identify their foreign country on Form 2555.5Internal 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. The stakes rise when treaty benefits are claimed: if Box 3a shows exemption code 04 or Box 3b shows a treaty-reduced rate, the country in Box 13b must be one that actually has a treaty with the United States. A non-treaty country in that box while claiming treaty benefits produces 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 whose aggregate balance exceeded $10,000 at any point during the calendar year.7Internal Revenue Service. FinCEN Form 114 – Report of Foreign Bank and Financial Accounts (FBAR) The country that matters is where the account itself is located, not where the financial institution is headquartered.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 requires country identification for each reported asset.9Internal Revenue Service. Do I Need to File Form 8938, Statement of Specified Foreign Financial Assets
Forms for Foreign Entities
Form 5471 (foreign corporations) requires codes on Schedule E for foreign taxes paid and 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 – Return of U.S. Persons With Respect to Certain Foreign Partnerships Form 926 requires the country code for the transferee corporation’s country of incorporation.12Internal Revenue Service. Instructions for Form 926 Form 3520 requires codes to identify the foreign trust’s jurisdiction.13Internal Revenue Service. Instructions for Form 3520 Annual Return To Report Transactions With Foreign Trusts and Receipt of Certain Foreign Gifts
What a Wrong Code Actually Costs
An incorrect code rarely produces a headline penalty on its own, but it cascades. On an e-filed return, an unrecognized code triggers rejection, and the return isn’t considered filed until you fix it and resubmit. Cross a deadline in the meantime and late-filing penalties start running.
For information returns like Form 1042-S, the IRS assesses penalties under IRC Section 6721 for filings with incorrect information. For returns due in 2026, the penalty is $340 per return, capped annually at $4,098,500 for larger businesses and $1,366,000 for businesses with average gross receipts of $5 million or less. Correcting within 30 days of the filing deadline drops the per-return figure to $60. Correcting before August 1 drops it to $130.14Internal Revenue Service. Revenue Procedure 2024-40 Intentional disregard pushes the penalty to $680 per return with no annual cap.15Office of the Law Revision Counsel. 26 U.S. Code 6721 – Failure to File Correct Information Returns
Form 8938 carries its own regime. A failure to file a complete and correct form can trigger a $10,000 penalty, with additional $10,000 increments accruing for continued noncompliance after IRS notice, up to $50,000 more. An understatement tied to an undisclosed foreign asset can draw an accuracy-related penalty of 40% of the underpayment.16Internal Revenue Service. Instructions for Form 8938 Statement of Specified Foreign Financial Assets
The bigger risk with a wrong code is not the code fine, it’s the collateral damage. If you claimed treaty-reduced withholding on Form 1042-S but entered a non-treaty country code, the IRS may treat the withholding as insufficient and pursue the additional tax against the recipient.
Staying Current With Changes
The IRS doesn’t update the country code list on a fixed schedule. Revisions reflect geopolitical events like new countries, name changes, and territorial reorganizations, along with administrative additions like the 2024 “US” code. Official guidance flows through the Internal Revenue Bulletin, published weekly.17Internal Revenue Service. Internal Revenue Bulletins
The practical habit is simpler: bookmark IRS.gov/CountryCodes and open it at the start of each filing season, and again before any one-off foreign filing. The page shows its last review date, so you can see immediately whether it has moved since you last checked. Thirty seconds of verification eliminates the most common source of preventable rejections.