At the beginning of every tax season, the American Institute of Certified Public Accountants presents a risk management webcast advising its members of potential problems tax practitioners may face in the coming tax season. This year there is a new risk — the U.S. Postal Service has changed the rules regarding postmarks. Â
For years, the longstanding rule was that a tax return is timely filed and a payment is considered timely if mailed by the due date. To be more precise, timeliness is established when a tax return or payment voucher is properly addressed, has adequate postage, is deposited with the post office by the due date, and finally, is postmarked by the due date.
Historically, the postmark reflected the date the item was deposited in the mail. However, last November, USPS issued FR-Doc. 2025-20740, which changed the definition of a postmark and when postmarks are applied for items mailed on or after Dec. 24, 2025.
While there are changes affecting the manner in which postmarks are applied, the most substantive change is that the postmarked date no longer reflects the date the item was deposited in the mail, but rather the day on which the item was first processed by USPS. This was certainly a lump of coal in the Christmas stockings of those who rely on USPS to establish timely mailing.
The AICPA warns that the date that an item is first processed can, in some instances, be days after the item was placed in the mail. Because the IRS and most other tax agencies rely on the postmark date to establish timely filing, documents that were placed in the mail on time may now be treated as filed late. This could potentially subject taxpayers to penalties and interest charges.
I am a semi-retired CPA, but I still serve a few clients whom I have served for decades. While I encourage all of my clients to file their tax returns electronically and to make payments through the webpay portals established by the tax authorities, several of my clients are elderly and do not trust technology. They prefer to use time-tested ways, which are more familiar and seem safer.
If you are so inclined, you need to consider that you are relying on two agencies (USPS and the IRS) that presently face extreme resource challenges. Since the pandemic, I have seen an increased number of situations where items sent via certified mail have been lost or stolen in the mail. I have also seen situations where an item was delivered, but the tax authorities failed to process that item. This is why the AICPA recommends using electronic filing and payment options whenever available.
Unfortunately, there are some situations where time-sensitive documents cannot be sent electronically. The AICPA recommends that, if you must use snail mail to send tax returns, documents or payments to tax authorities, you use certified mail, return receipt requested, and that you mail the items several days before the due date. The AICPA has also provided the following additional tips:
• Avoid placing deadline‑sensitive mail in USPS collection boxes close to due dates.
• Do not rely on customer-applied pre-printed labels (e.g., from self-service kiosks or postage meters).
• Obtain proof of mailing for deadline‑driven documents.
• Obtain a postage validation imprint by paying for postage at the USPS retail counter.
• Request a manual postmark at the USPS retail counter.
Please note that, under IRS procedural regulations, which are followed by the courts, certified mail is generally the only acceptable proof of timely filing if a tax return is lost or delayed by the post office.
In June, Californians will be voting by mail in the state primary election and the new postmark rules will apply. Several politicians, mostly Democrats, have voiced concerns that the USPS changes are politically motivated. When USPS was considering adopting the changes set forth in Notice FR-Doc. 2025-20740, numerous commentators suggested that voters would be disadvantaged and discouraged from voting because they would need to wait in line at the post office and pay extra for certified mail. The USPS was not sympathetic to those comments. They responded that election administration is not a USPS concern, rather it’s a matter for election officials to preside over.
Irrespective of politics, it is truly amazing how something as simple as mailing stuff has become so complicated. As a reminder, property taxes are due by April 10 and income tax returns are due five days later.
Jim de Bree is a Valencia resident.
