The Maryland Notice of Assessment Explained

In a reassessment year, SDAT mails every property owner in the region under review a Notice of Assessment — typically in late December. The notice is the document that starts the 45-day appeal clock, and it is also the single most misread document in the Maryland system, because it shows two different values that mean two different things.

What is on it

• The old value and the new value, side by side. The notice discloses both the current (phased-in) assessment and the value SDAT found at the review. This pairing is Maryland’s signature: no other state’s notice shows the phase-in arithmetic on its face.
• The phase-in schedule. If the new value is higher, the amount that will be added to your taxable assessment each year for the next three years follows from it — one-third of the increase per year.
• The date of finality. The notice establishes January 1 as the date of finality for the coming taxable year — the moment the new value becomes legally fixed unless you appeal. Your 45 days to file with the Supervisor of Assessments run from the notice’s date, and the value is locked when the finality date passes without an appeal.
• Your appeal rights. The notice states the 45-day window and how to file — including SDAT’s online appeal form.

Worked example (illustrative)

Illustrative reading with made-up numbers — not a valuation and not your property.

1. Inputs from the notice: old assessment $240,000 (fully phased in); new value $280,000 — a $40,000 increase; notice dated December 26, 2026.
2. Step — the phase-in: one-third of $40,000 is about $13,333, so the taxable assessment becomes roughly $253,333 in the first year, $266,667 in the second, $280,000 in the third.
3. Step — the cap: if you have the homestead credit, the 10% limit on last year’s taxable assessment ($240,000 × 1.10 = $264,000) does not bind in year one or two — the phase-in is already holding the increase below 10% per year. The two mechanisms are complementary, not duplicative.
4. Step — the clock: an appeal must be filed with the Supervisor within 45 days of December 26 — around February 9, 2027. The value is final for the year on January 1 only if no appeal is filed.

What this tells you: the number to compare with your current bill is the first-year phased-in assessment, not the new value. And the appeal deadline is anchored to the notice date, not to January 1 — so a notice that arrives late still holds you to 45 days from its own date.

What it does not tell you: your tax rate (your county sets that later), what your bill will be (the phase-in and the cap both apply between the value and the bill), or whether the new value is right — that is a market-evidence question, the same kind of question an appeal answers.

Years without a notice

Two years out of every three, no notice arrives for your property. That does not reset anything: the value from your last notice continues (through its phase-in), and the petition for review is the standing mechanism for challenging it in an off-year. See the triennial cycle for how the regions rotate.

What to do after reading it

• Questions about the value or the property data: contact the Supervisor of Assessments for your county — informal resolution is part of the process, and the supervisor’s office holds the first hearing anyway.
• If that does not resolve it and you are within 45 days of the notice date: file the appeal — the ladder and its deadlines are here.