CP107: What It Means and How to Respond

What the notice actually says

CP107 tells the business that the IRS "made changes to your tax return because we found a miscalculation. As a result of these changes, your balance due also changed." The instructions: read the notice, compare its figures against the return, contact the IRS within 60 days if disagreeing, correct the taxpayer's own copy if agreeing, and pay by the payment due date. (For where CP107 sits among the other IRS notices, see the IRS Notice Library.)

IRS Publication 6209, Section 9 fixes the scope precisely: CP107 covers "Math error on Form 1042 resulting in a net balance due." The notice also points the taxpayer to Instructions for Form 1042 itself and, distinctively among this notice family, carries its own FAQ on the failure-to-deposit penalty — a mechanism the FUTA and employment-tax versions of this notice family (CP101, CP102, CP111, CP112) don't mention at all.

What actually triggered it

CP107 fires when the IRS's recomputation of the Form 1042 withholding liability — the amount of U.S.-source income paid to foreign persons, the applicable treaty or statutory withholding rate, or the total tax withheld and deposited — disagrees with what the return reported, and the recomputation produces a higher net balance due. Common causes include a treaty rate applied to a payment that doesn't actually qualify for it, income categorized under the wrong withholding-rate pool, or a deposit that didn't post to the correct period.

The failure-to-deposit penalty that can ride alongside CP107 is a separate finding, not automatically part of the math-error correction itself: IRS.gov's own FAQ states "when an employer fails to make a proper tax deposit, even if the failure is due to an error, we assess a 10% failure-to-deposit penalty," and notes the taxpayer "may or may not have received notice of the 10% penalty before receiving this notice." Before assuming both the corrected liability and any penalty are right, pull the account transcript for the 1042 period and compare deposit timing and amounts directly — the IRS Transcript Decoder shows exactly what posted.

Response deadline and what happens if you miss it

IRS.gov's own CP107 page states the window plainly: "Contact us within 60 days of the date of your notice if you disagree with the changes we made. Please have your account information available when you call." That's a real, structural difference from CP101 and CP102's 10-day window and CP117's 10-day window — all four notices were fetched and compared directly in the same research pass, and CP107 is the only one of the four with a 60-day figure. Neither IRS.gov nor Publication 6209 explains why Form 1042's balance-due notice gets a longer administrative window than the employment-tax versions; the 60 days is stated as IRS policy for this notice, not tied to a statutory provision the way CP11's 60-day right is.

Separately, interest and penalty timing run on their own clock regardless of the 60-day dispute window: "Interest begins to accrue on the unpaid deposit amount from the day the deposit was due until the day we receive the deposit in full," and "interest will begin to accrue on the penalty if you don't pay the penalty amount within 10 days of the date of the notice." Paying the full amount owed by the payment due date on the notice avoids any additional penalty; missing it adds a 5% failure-to-pay penalty on top of the 10% failure-to-deposit penalty already assessed.

The practitioner's actual next step

Separate the two issues CP107 can raise before responding: the math-error correction to the reported liability, and any failure-to-deposit penalty riding alongside it. They have different remedies — disagreeing with the corrected liability means contacting the IRS within 60 days per the notice's own instructions, while disputing the penalty specifically means requesting removal for reasonable cause, a process the penalty notice itself explains and which doesn't depend on the 60-day window for the underlying correction.

If the deposit timing is defensible — a deposit made correctly but misapplied, for instance — that's worth raising as reasonable cause on the penalty even if the underlying math-error correction itself is accepted. If full payment isn't feasible by the due date, prioritize it anyway if at all possible: paying the tax by the due date is the one action the notice states stops any additional penalty from accruing, even while a penalty dispute is pending.

What CP107 gets confused with — and why the distinction matters

CP107's direct mirror is CP117 — the identical Form 1042 recomputation, per Publication 6209's own table, netting an overpayment instead of a balance due. The two share the underlying review; they don't share a penalty exposure, since a failure-to-deposit penalty has no role to play on a notice that ends in a refund.

CP107 is easy to lump in with CP101 and CP102 as "just another BMF math-error balance-due letter," but the 60-day window and the failure-to-deposit penalty make it materially different to actually work. A preparer used to the 10-day CP101/CP102 pattern who assumes CP107 runs the same short clock has more time than they think — but should not mistake that longer window for lower stakes, since the penalty exposure CP107 can carry has no equivalent on either of those notices.

CP107 is also worth separating from the individual math-error notices this site covers, CP11 and CP12 — both carry the statutory 60-day abatement right under IRC §6213(b)(2)(A), and CP107's own 60-day window matches that number exactly. Whether that match reflects the same statutory mechanism or a coincidence of administrative policy isn't settled by anything on the notice itself: CP107 carries none of the abatement-request language CP11 and CP12 both state directly, so treat the 60 days as this specific notice's own deadline rather than assume it carries the formal §6213(b)(2) right until the notice itself says otherwise.

The IRS can assess Chapter 3 withholding tax — the §1441/§1461 regime CP107 corrects — and litigate disputes over it through the Tax Court's ordinary deficiency procedures. IRM 8.17.4.28.6, "Tax Required to be Withheld at Source (Form 1042)," states it directly: "Adjustments to Form 1042 are subject to deficiency procedures," with Letter 901 the standard notice-of-deficiency letter used for it. AmBase Corp. v. Commissioner, T.C. Memo. 2001-122, shows the mechanism actually working: the IRS issued a statutory notice of deficiency for §1441/§1461 withholding tax reported on the taxpayer's own Forms 1042, and the Tax Court decided the case on the merits under its standard deficiency jurisdiction. That settles the question this page once left open about whether Form 1042 withholding sits inside the deficiency framework at all — it does.

Whether CP107 itself runs through IRC §6213(b)(1) specifically — the provision the Math and Taxpayer Help Act amends — is a narrower question AmBase doesn't answer. CP107's own text tells the taxpayer to pay the balance by the due date while separately inviting a 60-day call if they disagree, with no abatement-request language and nothing that pauses assessment or collection while a dispute is pending, unlike CP11 and CP12. That's this site's own read of how the notice is structured, not a citation to a ruling or IRS guidance stating the point outright — it's why the Math and Taxpayer Help Act likely still doesn't reach CP107 despite Form 1042 withholding being deficiency-eligible tax.

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