What Letter 1948-C is
The letter the penalty unit sends when your reasonable-cause response is missing something: a signature, the penalties-of-perjury statement, proof of solicitations, or an answer to one of the two questions (did you react timely, did you prevent recurrence). Per IRM 4.19.25.13 a case is suspended for this only once.
Where this sits: CP2100 (the mismatch list) → B-Notices to payees → Notice 972CG a year later (the proposed penalty) → CP15 or CP215 if it isn't waived (the assessment) → CP504 if it isn't paid (collection). Letters 1948-C, 854-C and 6304-C are the IRS's replies to your 972CG response.
The deadline
30 days (60 outside the U.S.). A second incomplete reply goes to assessment.
What to do
Send everything asked for in one package, signed by an officer. If proof of solicitations is requested, send the dated letters and the mailing log, and state that annual solicitations went by mail or phone.
What the examiner is usually missing
A 972CG response is checked against a short list before anyone weighs its merits: is it signed by the taxpayer or an authorized representative, does it contain the penalties-of-perjury declaration, does it address each failure type on the notice (late, paper when e-file was required, missing TIN, incorrect TIN), and for TIN failures does it show the solicitations the regulations require (the initial request at account opening and the annual solicitations after a notice). A response that fails one of those checks is not denied; it is suspended once, and Letter 1948-C goes out listing what is missing. The examiner is also told to ask the two reasonable-cause questions if the statement does not answer them: did you act responsibly when you discovered the failure, and what did you do to stop it recurring. A second incomplete reply is not suspended again; the case goes to assessment and the Letter 854-C denial follows.
Sending one complete package
Answer every item in the letter in one mailing, even the ones you think you already covered, and send it so you can prove the date. If a signature or the perjury declaration was missing, re-sign the whole statement rather than sending a signature page. If proof of solicitation was requested, send the dated W-9 requests or B-Notices for each payee on the notice, the mailing log or certified-mail receipts, and a sentence stating how the annual solicitations were made; the IRS accepts mail and telephone solicitations and treats purely electronic ones with suspicion unless the payee consented to electronic delivery, so say which it was. If the letter asks the two questions, answer them directly and in that order, with dates. Have an officer sign. The response guide lists the checks in the examiner's order, and the templates include a reasonable-cause statement built around them; the 972CG guide covers the solicitation rules the proof has to match.
Questions about Letter 1948-C
Who receives Letter 1948-C?
Payer. The letter the penalty unit sends when your reasonable-cause response is missing something: a signature, the penalties-of-perjury statement, proof of solicitations, or an answer to one of the two questions (did you…
What is the deadline on Letter 1948-C?
30 days (60 outside the U.S.). A second incomplete reply goes to assessment.
What should I do when Letter 1948-C arrives?
Send everything asked for in one package, signed by an officer. If proof of solicitations is requested, send the dated letters and the mailing log, and state that annual solicitations went by mail or phone.
Is Letter 1948-C about my own income tax?
No. This decoder covers information reporting and withholding: the notices a payer, filer or payee sees because of Forms 1099, W-2, 945 and the TINs on them. Individual income-tax notices follow a different track.
Have a different notice? The IRS notice decoder lists all 77 in the order they tend to arrive.