You got a supplemental or corrected appraisal notice — how to decode it

The spring cycle — notices in April and May, protests by the §41.44 deadline, certification of the roll generally by July 25 (§26.01) — only covers the property the district had fully processed by then. Everything else follows in waves: property discovered late goes into supplemental appraisal records under §25.23, property that escaped taxation entirely is back-assessed under §25.21, and values already on the roll get corrected, amended, or changed by order. Supplemental activity typically builds through August and peaks around September, and tax bills follow around October 1 (§31.01). If your parcel is in one of those waves, your notice — and your deadline — arrives off-season.

The single most useful fact about off-season notices: under §41.44, the protest deadline is May 15 or the 30th day after the notice was delivered, whichever is later — and for changes ordered after certification, the 30th day after the change notice (§41.44(a)(2)). A supplemental notice delivered September 3 is not a missed-May-15 problem; it carries its own deadline 30 days out. And the new value is fully protestable — the supplemental records are expressly subject to review, protest, and appeal under Chapters 41 and 42 (§25.23), so the unequal-appraisal (equity) ground of §41.43(b)(3) applies to a September value exactly as it does to an April one. The mechanics are in how the unequal-appraisal protest works.

Off-season values deserve the same scrutiny as spring ones — arguably more. A value set in the supplemental cycle (a new building’s first assessment, a back-assessed entry, a corrected figure) is generated outside the main mass-appraisal pass, and the only check on it is the owner reading the notice inside the window.

The window is short, but the work is small. First, mark the deadline: the 30th day after delivery. Second, look at what changed — the new value against last year’s, and the implied assessed $/SF against comparable properties. The free parcel lookup runs that comparison in about a minute — an informational estimate, not an appraisal. Third, if the number looks out of line, file the Comptroller’s Form 50-132 with your county’s ARB before the 30th day, checking every ground that applies; the full sequence from filing through the hearing is covered in the self-file protest guide and the ARB hearing preparation guide. For evidence, the flat-fee packet (from $299) assembles the §41.43(b)(3) comparable-median study for the parcel — you review it and file for yourself, and the fee never depends on the outcome.

Two adjacent situations have their own guides: if the 30 days already ran out, see what your options are after a missed deadline; and if the notice reflects an outright error — a duplicate account, the wrong owner, a building that does not exist — see correcting the roll under §25.25.