The Clock is Ticking: New USPS Postmark Rule May Affect Year-End Giving
As we approach the final days of December, nonprofits and donors alike are used to the “New Year’s Eve dash” to get checks in the mail. Traditionally, as long as a donor dropped their envelope in a blue collection box by December 31, the postmark would reflect that date and the IRS would count the gift for the current tax year.
A USPS rule effective December 24, 2025, is changing the game for year-end giving. Here is what your organization and your donors need to know to ensure no gift — or tax deduction — is left behind.
What Changed
In the past, mail was often postmarked at the local office where it was dropped off on the day it was mailed. Under the new rule, the USPS has clarified that a postmark now represents the date of the first automated processing operation at a regional facility.
Because mail is now often transported to these regional hubs before being stamped, the date on the envelope may be one to three days later than the day it was actually mailed. If a donor drops a check in a mailbox on December 31, it might not be processed — and thus not postmarked — until January 2 or 3.
Why It Matters
For a donation to be deductible in 2025, the IRS requires it to be “delivered” by December 31. For mailed checks, the postmark date is the legal proof of delivery.
The Risk: If a donor's check carries a 2026 postmark, they cannot legally claim it on their 2025 taxes — regardless of when they wrote the check.
The Friction: This can lead to frustrated donors and awkward conversations when year-end tax receipts don’t match a donor’s expectations.
How to Protect Your Donors
To ensure your supporters get the tax credit they intend, consider sharing these three “Safe Harbor” tips in your final year-end appeals:
Go to the Counter: Encourage donors who mail checks after December 26 to visit a post office in person and request a manual (hand-stamped) postmark. This guarantees the date reflects the actual day of mailing.
Use Certified Mail: Purchasing a “Certificate of Mailing” or using Certified Mail provides a dated receipt that serves as proof of the mailing date for the IRS.
Give Online: The simplest solution is to remind donors that gifts made through your website are effective the moment the transaction is processed — right up until 11:59 p.m. on December 31 for those who like to ring in the new year with a donation. Better would be to not wait until the ball drops in Times Square!
Talk to your Auxilio Partner Strategist if you need more guidance on communicating the USPS changes to your donors. If you’re not yet an Auxilio client partner, contact us to learn how we can serve your church or faith-based nonprofit by reducing your administrative burden to free you up for ministry.
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