The USPS recently clarified an important change that could affect taxpayers, nonprofits, and anyone relying on year-end mailings:
A postmark now reflects only the date USPS processes a piece of mail, not necessarily the date you mailed it.
Because many processing centers now handle mail one day or more after collection, the postmark on your envelope may show a later date than when you actually dropped it in the mailbox.
For most mail, this is a minor inconvenience. For tax filings and charitable contributions, the timing can have real financial consequences.
Why This Matters for Tax Documents
Many IRS deadlines rely on the long-standing “timely mailed, timely filed” rule. Under this rule, the postmark date generally determines whether your tax return or payment was sent on time. The difficult part is proving that you actually mailed it.
If USPS processes your envelope after the deadline, even if you mailed it before, your postmark may show a late date. That can lead to:
- Penalties
- Interest
- Processing delays
- Potential disputes regarding timely filing
The risk increases in late December and early January, when mail volume spikes and processing centers experience delays.
Certified Mail with Return Receipt: The Best Option
To ensure proof of timely mailing and receipt, we recommend sending all IRS correspondence via USPS Certified Mail with Return Receipt. Here’s why:
- Postmarked Receipt – When you send something via certified mail, the post office provides a receipt with a postmark, proving when it was mailed.
- Tracking Number – You receive a USPS tracking number to follow the package’s delivery status.
- Return Receipt (Green Card or Electronic) – When the IRS receives the mail, someone signs for it, and you receive proof of delivery.
- Certified mail provides legal protection in case the IRS disputes whether they received your documents timely.
Why It Matters for Year-End Charitable Donations
To claim a charitable contribution for a given tax year, donations generally must be mailed by December 31. The IRS typically uses the postmark date to determine whether your donation counts for that tax year.
If USPS doesn’t process your envelope until January 1 or later, the postmark could show the new tax year, even if you mailed it on December 31. This could shift your deduction into the following year or disallow it for the year you intended.
Ensure Accurate Postmarking
If the date matters, especially in late December, consider these steps:
1. Request a Hand-Stamped Postmark at the USPS Counter
As mentioned above, the best way to ensure your postmark aligns with the correct mailing date is to visit your local post office in person. A hand-stamped postmark reflects the exact day USPS receives your mail, avoiding processing delays that could push the date forward.
2. Use Certified Mail, a Certificate of Mailing, or Priority Mail
These services provide an official acceptance date, which can serve as proof of timeliness and reduce the risk of disputes.
3. Avoid Late-Day Drop-Offs Near Weekends or Holidays
Mail deposited late in the day or close to non-processing days is more likely to be processed the next business day, resulting in a later postmark.
Bottom Line
This USPS clarification doesn’t change IRS rules, but it does change how reliably a postmark reflects the date you expect. If a filing deadline or donation cutoff is important, taking the time to visit your post office in person can help prevent penalties, disputes, or lost deductions.
If your organization handles year-end giving or tax-sensitive mail, consider updating your internal guidance to reflect these changes. You may also want to remind donors or clients to plan ahead during the high-volume holiday period.
