IRS Letter 4087C (LTR 4087C): What It Means and How to Fax Your Reply

What IRS Letter 4087C means

Letter 4087C is the IRS telling you that your international income tax return is on hold until you send more information. The IRS page Understanding your letter 4087C puts it in one line: "We need more information to process your international income tax return."

Inside the IRS, the letter carries the title "International Return Incomplete for Processing." The IRS manual on refund research (IRM 21.4.1) lists it for international taxpayers who filed Form 1040-NR, Form 1040 or Form 1040-SR, along with some older return types.

According to irs.gov, the IRS may be asking for one or more of these:

• Missing or corrected forms or schedules that support the entries on your Form 1040, Form 1040-NR or Form 1040-SR.
• Verification of your income, withholding and credit amounts.
• Verification of taxpayer identification numbers or Social Security numbers.

A missing signature is another reason. The IRS manual for international return processing (IRM 3.22.3) says: "Use Letter 4087C to request the taxpayer's signature."

Your letter names exactly which of these applies to you. Read the request line by line before you gather anything, because the reviewer can only act on the items the letter asked for.

Where to find the Letter 4087C fax number

The fax number for a Letter 4087C reply is the one printed on your letter. The irs.gov page for Letter 4087C lists no fax number, and we do not publish one here, because a number copied from somewhere else may not reach the unit handling your return.

Look for the response instructions in the letter. If they give a fax number, type it exactly as printed, then read it back against the letter once before you send. Write the same number on your cover sheet so your packet carries a paper record of where it went.

If your letter lists no fax number, or a page is missing, do not guess. Use the contact details on the letter. The IRS manual tells its phone staff to give callers with a Letter 12C or 4087C the correct reply address or fax number (IRM 21.4.1). If you never received the letter at all, irs.gov points you to Let us help you.

Fax numbers for other IRS forms are a separate question. If you are sending a form rather than replying to a letter, see our list of IRS fax numbers by form.

What to send with your reply

Send exactly what your Letter 4087C asks for, and nothing that replaces your original return. Irs.gov says to read your letter carefully, send the requested information within 30 days, and not to file Form 1040-X.

A clear packet usually looks like this:

1. A cover sheet with your name, the tax year, the letter number (4087C) and the total page count.
2. A copy of the letter, so the reviewer can match your pages to the request.
3. The items the letter asked for, such as the missing form or schedule, the corrected form, or the document that verifies an income, withholding or credit amount.
4. A short written explanation if you disagree with anything. Irs.gov asks you to respond even if you disagree, "providing a clear explanation of what you disagree with."
5. Your signature, if the letter asks you to sign.

Send copies, not originals you cannot replace. Number every page (1 of 6, 2 of 6) so a dropped sheet is easy to spot.

How to fax your 4087C reply step by step

You can fax a 4087C reply without a fax machine. The receiving fax line sees an ordinary fax whether it came from a machine, a browser or a phone.

Faxend Basic costs $9.99 one time for up to 10 pages, with no subscription. If you expect more IRS letters this year, Standard is $9.99 a month for 50 pages and adds fax receiving. Current details are on the pricing page. If this is the only fax you plan to send, you can also compare one-time fax services.

Deadline and what happens after you reply

Irs.gov asks you to send the requested information within 30 days. Check the date printed on your own letter as well, and send early if you can.

Once the IRS has your reply, irs.gov says it will send any refund due about 6 to 8 weeks after it receives your response. That clock starts when your reply arrives, so a faxed reply starts it sooner than one still in the mail.

If you need help, irs.gov lists three routes on the same page:

• Authorize someone to represent you before the IRS.
• The Taxpayer Advocate Service, an independent office inside the IRS.
• A Low Income Taxpayer Clinic, if you qualify.

For next year, the IRS suggests providing complete information to support your entries, using the correct forms and schedules, checking every SSN and ITIN for accuracy, and keeping copies of your returns and IRS correspondence.

Letter 12C vs Letter 4087C

Letter 12C and Letter 4087C ask for the same kinds of information. The difference is the type of return and the response window: 12C is for individual returns, 4087C is for international returns.

Sources: Understanding your Letter 12C, Understanding your letter 4087C and IRM 21.4.1.

Letter 324C is a different letter. It concerns an amended return that is missing information, not an original return. If that is the letter you have, read our guide to faxing a response to IRS Letter 324C.

Frequently asked questions

What is IRS Letter 4087C?

Letter 4087C means the IRS needs more information to process your international income tax return. It may ask for missing or corrected forms or schedules, verification of income, withholding or credit amounts, or verification of taxpayer identification numbers.

What is the fax number for IRS Letter 4087C?

Use the fax number printed on your letter. The irs.gov page for Letter 4087C does not list a fax number, so a number found elsewhere may not reach the unit handling your return.

How long do I have to respond to Letter 4087C?

Irs.gov asks you to send the requested information within 30 days. Check the date on your letter and reply even if you disagree, with a clear explanation of what you disagree with.

What is the difference between Letter 12C and Letter 4087C?

Letter 12C is for individual returns (Form 1040 or 1040-SR) and irs.gov gives 20 days to respond. Letter 4087C is for international returns, including Form 1040-NR, and irs.gov gives 30 days.

Should I file Form 1040-X after receiving Letter 4087C?

No. Irs.gov says not to file Form 1040-X. Send the information the letter requests instead.

Can I fax my Letter 4087C reply from my phone?

Yes. With Faxend you photograph or upload each page, enter the fax number printed on your letter, and keep the send confirmation. A one time send of up to 10 pages is $9.99 with no subscription.