Notice code Letter 12C
You got Letter 12C. Send what the IRS asks for in 20 days.
You are holding IRS Letter 12C, and your return is on hold until you answer it.
The IRS needs more information to process your return, and you have 20 days to send it.
Use the form to send your 12C, and a licensed tax professional can help get the papers in on time.
Briefing for Letter 12C
IRS pageThe IRS is asking for missing information before it can finish your return.
Example20 days from a letter dated October 6, 2026 is October 26, 2026.
- Send the missing forms or proof to the address on the letter.
- Reply with a written explanation if you disagree.
- Call the number on the letter if an item is unclear.
Which numbers matter?
20 days
The IRS wants the missing items fast, or your return stays stuck.
Mail everything the letter asks for before 20 days pass.
6 to 8 weeks
Any refund you are owed comes about 6 to 8 weeks after the IRS gets your reply.
Send your reply early so the refund clock starts sooner.
Form 1040-X
Filing an amended return is the wrong move for this letter.
Answer the letter itself instead of filing Form 1040-X.
Get your 12C papers in on time
Letter 12C gives you 20 days to send the IRS the forms or proof it names.
Until then your return sits and your refund waits, but a licensed tax professional can gather the papers and reply.
Send your 12C through the form, or call now and sort out what is missing before day 20.
Call 855-964-5291What happens when you call
- You call during business hours and say you have an Letter 12C.
- A licensed tax professional asks for the date, the amount and the tax years on the letter.
- You hear your options for this notice and decide what to do. Nothing is filed without your yes.
A licensed tax professional answers, not the IRS. The call costs nothing, and you give up nothing by calling. IRS Code Lookup is a private tax help service.
Would you rather send your Letter 12C details?
Your 12C lists exactly which forms or proof the IRS is missing from your return.
With those details, a licensed tax professional can see what to gather and where to mail it.
What changed recently?
Since September 30, 2025, the IRS has stopped sending paper refund checks to individual taxpayers, with limited exceptions. Refunds now go out electronically, mainly by direct deposit.
Source: Questions and answers about Executive Order 14247 (paper refund checks).
What is the IRS saying?
The letter names what is missing. It might be a schedule, a form backing up an entry, proof of income or withholding, or a check of a Social Security number.
Why did you get it?
Something on the return could not be matched. Take Nia. She claimed a health coverage credit for 2025 and left out the form that supports it.
Is it real?
The letter lists exactly what to send and where. No payment is asked for.
Still unsure? Search the code on the IRS notice search, or use the real or fake checklist.
When is your deadline?
The IRS says send the information within 20 days. Reply even if you disagree, and say what you disagree with.
What if you agree?
Send the missing forms or proof to the address on the letter. Do not file Form 1040-X; answer the letter itself.
What if you don't agree?
Reply anyway with a clear explanation. Silence holds up the return.
What happens if you ignore it?
The return stays unprocessed and any refund waits.
What should you read next?
Questions people ask
How long does Letter 12C take after I reply?
The IRS says it sends any refund due about 6 to 8 weeks after it receives your response.
Should I file an amended return for Letter 12C?
No. The IRS says not to file Form 1040-X. Answer the letter.
What if I disagree with Letter 12C?
Reply within 20 days anyway and explain what you disagree with.
Is Letter 12C an audit?
No. It asks for missing items so the IRS can finish processing.
Sources
- Understanding your Letter 12C. Published by irs.gov.
- Questions and answers about Executive Order 14247 (paper refund checks). Published by irs.gov.
Last checked October 2026
What to do now
- Read the letter and list every item it asks for.
- Gather the missing schedules, forms, or proof of income and withholding.
- Mail them to the address on the letter before 20 days pass.
- Do not file Form 1040-X, and explain in writing anything you disagree with.
Send your 12C through the form, or call now and sort out what is missing before day 20.
A licensed tax professional answers, not the IRS. The call costs nothing, and you give up nothing by calling. IRS Code Lookup is a private tax help service.