Baltimore County, Maryland Property Tax Appeal Guide for 2027

What deadline matters first

For Baltimore County Area 3 homes in the regular 2027 reassessment cycle, treat February 13, 2027 as the expected deadline if SDAT dates the reassessment notice December 30, 2026. Maryland gives you 45 days from the notice date to file, and the deadline printed on your SDAT notice controls. SDAT lists Baltimore County Area 3 as effective January 1, 2027, and the online Real Property Assessment Appeal Form says to file within 45 days of the notice date (SDAT appeal form, Baltimore County reassessment areas).

Baltimore County is assessed by Maryland SDAT, not by a county assessor. Your first filing goes to the Baltimore County Supervisor of Assessments. SDAT says you can file online with the notice number and control number, or return the appeal form that comes with the notice (SDAT appeal form).

SDAT lists hearing options as written, phone, video, and in-person. If the supervisor decision is not favorable, further review may go to the Property Tax Assessment Appeal Board and then the Maryland Tax Court, with separate follow-up deadlines after each decision (SDAT Assessment Appeal Process).

For tax-rate context only, SDAT’s 2025-2026 table lists Baltimore County’s countywide nonmunicipal real-property rate as $1.1000 per $100 plus the Maryland state rate of $0.1120 per $100. That is about 1.212% combined before municipal, special-district, exemption, credit, or Homestead effects. The same table lists Baltimore County’s local Homestead credit cap as 4% (SDAT 2025-2026 tax rates).

For volume context, Maryland’s Property Tax Assessment Appeals Boards reported an appeal count of 8,578 appeals received in calendar year 2024, with 9,000 estimated for 2025 and 9,500 estimated for 2026 (Maryland DBM FY 2027 PTAAB Managing for Results).

The common value appeal

The common homeowner filing reason is Total New Market Value is incorrect. Use this when you believe SDAT’s Total New Market Value is higher than the property’s fair market value as of the January 1, 2027 date of finality.

In plain English, you are not arguing that the tax bill is painful or that the increase feels too large. You are arguing that the market value SDAT assigned is not supported by the facts. SDAT says useful points include value-affecting facts, worksheet errors, inaccurate property characteristics, and comparable sales that support your claimed value (SDAT Assessment Appeal Process).

The January 1, 2027 date matters because Maryland values real property on the January 1 date of finality before the first taxable year to which the new value applies. For Baltimore County Area 3, the policy record identifies the 2027 reassessment as effective January 1, 2027 (Baltimore County reassessment areas).

Other reasons you might appeal

Classification is incorrect means the property is in the wrong assessment classification. This is not about whether you like the amount of the assessment. It is about whether SDAT placed the property in the correct official class.

Worksheet, measurement, mathematical, clerical, or technical error means SDAT’s record has an objective problem that affects the assessment. Examples include an incorrect improvement detail, wrong measurement, math issue, clerical mistake, or another technical record error.

Inequality of assessment means comparable properties are assessed differently in a way that supports an inequality argument. If you rely on other properties at the Maryland Tax Court level, Rule 7 requires an itemized list served at least 10 days before the hearing, and sale evidence must state the sale date and sale price (COMAR 14.12.01.07).

Income method / income-producing property valuation applies to income-producing real property. SDAT warns that income and expense information should be submitted at the supervisor level to preserve an income-method issue for later appeal levels (SDAT Assessment Appeal Process).

If your Notice of Assessment says something else changed

A Notice of Assessment is SDAT’s written notice showing your property’s new assessment information. It may show the old value, the new value, identifying numbers, and instructions for filing. SDAT’s online appeal form uses the notice number and control number from page 1 of the assessment notice (SDAT appeal form).

If the Notice of Assessment says a property fact changed, slow down and check that fact. A changed building area, construction detail, property characteristic, or classification can matter because SDAT’s value may be built from those records.

You can request the property worksheet and comparable property worksheets. SDAT’s assessment notice explanation says the notice form has built-in space to request comparable property worksheets and says to attach an additional sheet if more space is needed (SDAT Assessment Notice Explanation).

What evidence helps

Start with evidence tied to the January 1, 2027 valuation date. For Baltimore County Area 3, the structured evidence window is January 1, 2024 through January 1, 2027, with the strongest sales usually closest to January 1, 2027.

Use arm’s-length closed sales of properties that are as similar and close as possible. Look for similar location, age, style, condition, size, lot utility, and other value-affecting features. Maryland and SDAT sources do not publish a fixed Baltimore County numeric comparable-sale radius, size variance, lot-size variance, or cap on the number of comparable sales.

For each comparable sale, write down the property address or account identifier, sale date, sale price, and the reason it is comparable. If a sale is unusual, such as a family transfer, distress sale, or another non-market transaction, do not treat it as a clean indicator unless you can explain why it still reflects market value.

Helpful non-sale evidence can include photos, repair estimates for condition problems, permits, appraisals, listing information, and SDAT worksheet corrections. Avoid relying only on past values, the percent increase, the tax-bill amount, metropolitan costs, or complaints about government services. SDAT identifies those kinds of arguments as not relevant to the value under appeal (SDAT Assessment Appeal Process).

What the board can and cannot decide

The Baltimore County Supervisor of Assessments is the first review level. The supervisor can consider whether the assessment value, classification, worksheet facts, and supporting evidence justify a change under SDAT’s assessment rules.

If you disagree with the supervisor’s final decision, the next appeal body is the Property Tax Assessment Appeal Board. PTAAB describes the board as independent from SDAT, and says a property owner has 30 days from the SDAT decision to appeal to the local board (PTAAB home page).

The board can decide assessment issues. It cannot change the tax rate, rewrite the county budget, decide whether public services are adequate, or reduce a bill simply because the increase is hard to afford. Those concerns may be real, but they are not the same as proving the assessment is wrong.

If you are dissatisfied with the Property Tax Assessment Appeal Board decision, SDAT says you may appeal to the Maryland Tax Court within 30 days of the PTAAB order (SDAT Assessment Appeal Process).

How TaxSauce helps

TaxSauce helps you turn a confusing SDAT notice into an organized review. We help identify the filing deadline, the official reason that best matches your concern, and the evidence that should be gathered before you submit.

For a Total New Market Value is incorrect filing, TaxSauce can estimate whether nearby sales appear to support a lower value. We can also help organize comparable sales, worksheet issues, photos, and notes into a packet you can review.

You stay in control of the filing. TaxSauce can help prepare and organize the materials, but you choose what to include and submit through SDAT’s official filing option. No service can promise a reduction, a particular hearing result, or that SDAT or a later board will accept every argument.