Every practitioner has had this conversation with a client: "I never got that letter from the IRS." Usually, that's treated as the client's problem. A new Tax Court decision says it can just as easily be the IRS's problem, and it hands practitioners a concrete, repeatable way to make it one.
In Dania Wales v. Commissioner (T.C. Memo. 2026-82, decided September 3, 2026), the taxpayer had filed a Form 8857 requesting innocent spouse relief in August 2023. After more than two years with no response, she petitioned the Tax Court under the "six-month rule," which lets a taxpayer go straight to court if the IRS hasn't resolved the request within six months. The IRS moved to dismiss, claiming it had actually mailed a Final Determination Notice by certified mail back in February 2025, which, if true, would have started a strict 90-day clock that expired long before she filed.
The IRS's proof fell apart under scrutiny. It couldn't produce a USPS Form 3877, the certified mailing log that normally establishes a presumption of proper mailing. Instead, it offered a copy of the notice, a returned envelope marked "unclaimed," and USPS tracking data. The problem: the actual envelope showed presorted first-class postage with no certified mail marking, and neither the tracking history nor a USPS certification stated the item had been sent by certified or registered mail at all. The Tax Court held that none of this secondary evidence met the government's burden, ruled the 90-day deadline was never triggered, and denied the motion to dismiss.
Why this matters beyond innocent spouse cases. The same certified-mailing proof requirement governs other jurisdictional deadlines tied to IRS mailings, including deficiency notices. Wales confirms that when the IRS can't produce a proper Form 3877 or equivalent certified mailing record, tracking numbers and "unclaimed" envelope stamps aren't a substitute, and the taxpayer's filing window may never have started running in the first place.
What to do when a client disputes an IRS notice. Before conceding that a filing deadline has passed, request the underlying mailing documentation, specifically Form 3877 or its computerized equivalent, rather than accepting the IRS's stated mailing date at face value. Inspect any physical envelope in the file for actual certified or registered mail markings; presorted first-class postage is not certified mail, regardless of what the notice itself says. If the IRS can't produce that documentation, the jurisdictional deadline argument is genuinely open to challenge.
This isn't a loophole that excuses ignoring IRS mail. It's a documentation fight, and it only works when the IRS's own paperwork is actually deficient. But for the client who insists they never got a notice, Wales is now a concrete, citable reason to push back before assuming the deadline has run.