I received a letter last April with identifier CP45 from IRS after filing for tax year 2022. I understand this is regarding the IRS indicating they won't apply a tax overpayment to this year's (2023) estimated tax payments. The letter indicated that more information would be sent along explaining the adjustment, but it never was...sigh.

The difference between what I had overpaid and the change(s) IRS made that reduced that amount available for this year's estimated payments, i.e. where they felt my filing was in error, was exactly $400.

Does anyone have a good guess, or maybe actual experience, with this situation? Not just the CP45 letter, with is mostly informational, but such a round number of $400? Obviously, there is no point in actually calling them at the number on the letter (life is short, after all), so no need to suggest. Thanks...

  • Round number is perfectly reasonable if you had a math error on your forms. Even if random the odds against it are only 1 in 100 so it's quite possible.
    – keshlam
    Feb 25, 2023 at 14:50
  • @keshlam: yep...I wondered about that, but a search through my return for an amount = exactly $400 did not find anything. My taxes are simple, and I use Turbotax, so while it's >possible< that a mistake was made and that it equaled exactly $400, I think it's >really< unlikely. I think there is probably another reason or explanation, hence my OP. Thanks for replying :--)
    – AA040371
    Feb 25, 2023 at 16:23
  • All it takes is a one-digit error in one of the numbers, and the digit doesn't have to be 4, just 4 away from being correct.
    – keshlam
    Feb 25, 2023 at 17:12
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    You should absolutely call them. They are in fact answering their phones nowadays.
    – littleadv
    Feb 25, 2023 at 19:35
  • @littleadv: Ok, OK...I'll try! (lol) If they even answer in a timely manner I'll mark your answer as "the answer". Otherwise you owe me beer :--)
    – AA040371
    Feb 26, 2023 at 1:02

2 Answers 2


From the IRS:

How can I find out what happened on my tax return this year that would cause this change?

Please contact us at the number listed on your notice for the specific information concerning your tax return.

So yes, call. They do answer their phones, and since the Biden's budget increase they were able to hire 5000 more phone reps. The wait time now should be manageable:

In addition, practitioners can call the general IRS help line number — 800-829-1040 — which has a wait time of under 12 minutes, Corbin said.

  • Strictly speaking the significant new IRS funding was in the optimistically (if not fantastically) named Inflation Reduction Act, not the budget and (eventually) enacted Consolidated Appropriations Act, but that doesn't alter the result. Feb 26, 2023 at 5:14
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    It turns out that the $400 was a "bad check" fee that was applied to an estimated tax payment I made electronically that my bank SNAFU'd. lol...$400 because an EFT failed. Anyhoo...I found out by calling them, and I didn't have to wait long at all. So thanks for the tip.
    – AA040371
    Feb 27, 2023 at 17:28

In addition to improved chance now of reaching them by phone, you can request a "record of account" transcript. This shows the major line items from your return -- compare them to the return you (tried to) file for any differences, which IRS may have done for a 'math error correction', although you should have received a notice for such -- AND any subsequent changes they posted (although for any change due to 'audit' or even 'error resolution' you should have received several notices).

If you pass their (outsourced) security screening -- or if you have already done so to get an 'online account' -- you can do this online, instantly. Otherwise you may need to have it mailed to you, which will take a few weeks, but as long as you don't use the paper request it is automated and won't have to wait for a human.

  • @dave-thompson-085: thanks...to make clear, I received the original letter telling of the markdown of $400 about a year ago, but have never received anything further communication, in particular something explaining the >>why<< of it. And I am aware of the ID.Me option, but am more than a little nervous about it, for obvious reasons.
    – AA040371
    Feb 26, 2023 at 13:46
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    mblatz01: personally I feel with the scrutiny id.me is under they're safer than average -- certainly more than IRS inhouse apps which had several confirmed breaches, as well as OPM Equifax TMobile FaceSteal TwitLie GooGrab and so on. But as I said there is the alternative of having a transcript mailed -- because this goes to your address of record, not an address potentially entered by a fraudster, they accept lower security for the request and in particular no id.me -- although on rechecking I see you must do separate return ts and account ts. But I seee this is now moot anyway. Mar 2, 2023 at 5:45

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