The calendar year from the IRS standpoint starts on January 1 and ends on December 31. But what is the timezone?

For example, if a US taxpayer converts an after-tax 401(k) to a Roth 401(k) on December 31 at 23:59 UTC−11:00, 2017, does that count as December 31, 2017 or January 1, 2018?

  • 2
    When I logged into Fidelity at less than a hour before midnight local time (but was 2018 Eastern Time), only 2017 contributions were available.
    – RonJohn
    Commented Jan 1, 2018 at 20:50
  • It's a different thing but might be usable as an analogy: for e-filed returns IRS normally accepts the timestamp your return is (electronically) received by the authorized 'Transmitter' (e.g. Intuit etc.) adjusted to the timezone of your residence, see irs.gov/e-file-providers/electronic-postmark Commented Jan 3, 2018 at 11:29

1 Answer 1


I don't know of a federal rule regarding this, but in my experience financial transactions are based on the point of view of the transacting bank. In other words, whatever date the bank statement shows would be the official date.

  • 4
    Common sense says this must be the right answer since your bank statement is generally the evidence you'd expect to rely on should questions arise about your transaction...
    – user541686
    Commented Jan 2, 2018 at 12:23
  • @Mehrdad Thanks. What if I can prove that the taxable event to place on December 31 at 23:59 UTC−11:00, 2017? (e.g., email from the institution managing the 401(k) plan confirming that the action from the taxpayer was received). Does that count as December 31, 2017 or January 1, 2018? As a side note, the in-Roth 401(k) conversion was just an example. Another example: the taxpayer won 1kUSD at the casino on December 31 at 23:59 UTC−11:00, 2017. Commented Jan 2, 2018 at 20:20
  • @FranckDernoncourt - for transactions that banks report to the IRS, if what the bank reports doesn't match up with what you report, then the IRS will likely send you a letter with an updated tax liability and it would be up to you explain to them why you believe the bank date is "wrong". Similarly, for things that are not reported, then if audited it would be up to you explain to the auditor why your dates don't match up with the bank statements. Perhaps your example email documentation would satisfy them, perhaps not. (It seems reasonable to me.)
    – TTT
    Commented Jan 2, 2018 at 20:35
  • 1
    @TTT thanks good to know, but we go back to the timezone issue: which timezone does does IRS use? Commented Jan 2, 2018 at 20:43
  • 1
    @TTT I see. I just wanted to understand if the IRS has any time zone in mind (which could depends on the taxpayer location, for example). From your answer and your comments, I understand that as far as you know the IRS doesn't have any guideline on that matter. Thanks for your feedback! Commented Jan 2, 2018 at 21:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .