Letter 4384C: Wrong instrument: file a signed original, or use the X form

What Letter 4384C is

Accounts Management sends it in two Form 945 situations. First, when a Form 945-X arrives against a return the IRS prepared under IRC 6020(b): "The IRS has a policy against abating any portion of the tax assessed unless the taxpayer files an original signed tax return" (IRM 21.7.9.4.1.6.1(2), Oct. 1, 2026), so the letter asks for a signed Form 945. Second, when a second return posted, cannot be located, the payer did not reply to Letter 418C and the correct tax cannot be determined; the letter tells the payer that "in the future they must file the appropriate 'X' form" (IRM 21.7.9.4.1.2(7)).

The deadline

45-day suspense (IRM 21.7.9.4.1.6.1(3)). On no reply in the 6020(b) case the IRS builds a "dummy" original from your 945-X figures.

What to do

In the 6020(b) case, sign and file a complete Form 945 for the year with a Form 945-A; "the tax return reflecting the tax decrease is considered the original filing and a Form 94X-X tax return is not required" (IRM 21.7.9.4.1.6(5)). In the lost-return case, send a copy of the second return with proof of filing and state whether it was a duplicate, a correction or additional tax.

Original returns, X forms and substitutes for return

Since 2009 the employment tax returns have been corrected with a separate adjusted return rather than a second original: Form 945-X for Form 945, Form 941-X for Form 941 and so on. An X form reports the correction line by line against the return as originally filed, and it only works when there is an original return of yours on file to correct. Two situations break that pattern and produce Letter 4384C. In the first, you never filed a Form 945 for the year and the IRS prepared one for you under IRC 6020(b) from the withholding on your 1099s and W-2Gs; a 945-X filed against that substitute is the wrong instrument, because the IRS will not reduce a 6020(b) assessment on the strength of an adjusted return. It wants a signed original Form 945 from you, and that return is treated as the original filing, with no X form required. In the second, a second Form 945 for the same year reached the IRS, could not be matched to the first, and you did not answer the earlier letter asking which was right; the IRS cannot tell whether it was a duplicate, a correction or additional tax, and the 4384C tells you to use the X form for corrections in future.

Responding within the 45 days

In the 6020(b) case, prepare a complete Form 945 for the year, with a Form 945-A if you were a semiweekly depositor, sign it, and send it as the letter directs with a copy of the letter on top. Figures should come from your records, not from the IRS's substitute. If the response window closes without a return, the IRS builds an original from the figures on your 945-X, which may or may not be what you intended. In the duplicate-return case, send a copy of the second return with proof of when it was filed and a one-paragraph statement of what it was: an exact duplicate (ask that it be disregarded), a correction (ask that it be processed and say what changed), or additional tax for the period. The duplicate and superseding returns page covers how the campus treats each case, and the Form 945-X page covers when the X form is the right instrument and the three-year window for using it.

Questions about Letter 4384C

Have a different notice? The IRS notice decoder lists all 77 in the order they tend to arrive.