Montgomery County Property Assessment: How It Works and How to Appeal

Your Montgomery County property tax bill is calculated using an assessed value set by the Maryland State Department of Assessments and Taxation (SDAT) — not the price you paid. That assessed value may be too high. If it is, you're overpaying taxes every year until you appeal. Here's how the system works and how to challenge it. (For the underlying records — your current assessment, ownership history, and the tax account itself — see the Montgomery County property records lookup guide.)

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How SDAT Determines Your Assessed Value

Maryland uses a triennial reassessment cycle — every property in the state is reassessed once every three years. Montgomery County is divided into three groups. Each year, one-third of properties are reassessed. So your home is physically reassessed once every three years, regardless of whether the market has moved up, down, or sideways.

What SDAT looks at:

• Recent sale prices of comparable properties in your area
• Property characteristics: square footage, lot size, year built, bedroom/bathroom count, condition
• Any permits pulled for additions, renovations, or new construction
• Income approach for investment properties

SDAT assessors do not always physically inspect each property. In many cases, assessments are done as "drive-by" or desk reviews, which means condition and interior updates may not be fully captured.

Phase-in and the 10% cap are two different things. People often blend them together, so here they are separately:

• Phase-in (everyone): when a regular reassessment raises your value, the increase is phased in over the three years of the cycle. A decrease takes effect all at once.
• Homestead Tax Credit (principal residence only): separately, the Homestead Tax Credit caps the annual increase in your taxable assessment at 10% in Montgomery County (5% in the Town of Kensington). It applies only if you've filed the one-time application, and a new owner isn't eligible in the first full fiscal year of ownership.

So if your property was reassessed at a 30% increase, the phase-in spreads that over three years (about 10% a year), and the Homestead cap makes sure your taxable assessment doesn't rise more than 10% in any one year.

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Assessment vs. Market Value: Why They Differ

Your assessed value and your home's actual market value are almost never the same number.

In a rising market, assessed values lag behind reality. SDAT's reassessment uses sales data that may be 12–18 months old by the time your new assessment is set. Montgomery County home prices rose 6.6% year over year in March 2026 — that kind of appreciation means assessments set in 2024 may already be meaningfully below current market value for many homeowners.

The practical implication: overpayment is rare in a rising market because assessed values typically run below actual market values. But it does happen, particularly when:

• Your home has condition issues (deferred maintenance, structural problems) not reflected in the assessment
• Recent comparable sales were distorted by a few outlier high prices
• Your property has unique characteristics that make it less valuable than the "typical" home SDAT used for comparison
• You purchased the property and the new assessment came in higher than what you actually paid

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When to Consider Appealing

Appeal your assessment when:

1. Your assessed value is higher than what you'd realistically sell for today. If SDAT says your home is worth $700,000 but comparable sales tell you it would list at $640,000, you have a legitimate appeal.

2. You recently purchased the home and SDAT reassessed above your purchase price. An arm's-length sale is strong evidence of market value.

3. Your home has condition issues not reflected in the assessment. SDAT assessors working from data and drive-bys don't see water intrusion, HVAC age, or deferred maintenance.

4. Your assessment is materially higher than comparable properties on your street. Pull 3–5 comps from SDAT's own records. If you're assessed meaningfully higher than similar homes nearby, that inconsistency is grounds for appeal.

When NOT to appeal: If your assessed value is well below current market value, don't appeal — you'd potentially be inviting SDAT to increase your assessment. Appeals are decided on market value, not on how much your assessment or tax bill went up, and an appeal can result in an increase.

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How to Appeal Your Montgomery County Property Assessment

Maryland's assessment appeal process has three levels. Start at Level 1 and escalate only if needed.

Level 1: Supervisor's Level Appeal

Deadline: You have 45 days from the date on your notice of assessment to file a Level 1 appeal. This notice is mailed when SDAT reassesses your property (one-third of properties each year, in January), and also when SDAT revalues it out of cycle.

Two other ways to start an appeal:

• New-owner appeal: if the property transferred to you between January 1 and June 30, you can appeal within 60 days of the transfer.
• Petition for Review: in the two years of the cycle when your property isn't being reassessed, anyone can file by the first working day after January 1. It applies to the tax year starting the following July 1.

How to file: Complete the appeal form included with your assessment notice, or download it from SDAT's website. Submit by mail or in person to the local SDAT office for Montgomery County.

What happens: An SDAT supervisor reviews your evidence and compares it to their data. You may have an informal meeting. Many appeals are resolved at this level — often a modest reduction if your evidence is solid.

What to bring:

• 3–5 recent sales of comparable properties (same square footage, similar condition, within half a mile if possible, within the last 6–12 months)
• Documentation of condition issues (repair estimates, inspection reports, photos)
• Your actual purchase price if you recently bought the home
• Any appraisal you have

Level 2: Property Tax Assessment Appeals Board (PTAAB)

If you're not satisfied with the Level 1 outcome, you can appeal to the PTAAB within 30 days of receiving the Level 1 decision. This is a formal hearing with a three-member board. Evidence rules are more structured, but you do not need an attorney.

Level 3: Maryland Tax Court

The final administrative level. If the PTAAB rules against you, you can appeal to Maryland Tax Court within 30 days. This is a more formal proceeding. At this level, many homeowners hire a property tax attorney or consultant, particularly for high-value properties where the tax savings justify the cost.

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What a Successful Appeal Saves You

On a $700,000 property with a $50,000 reduction in assessed value:

• Combined State and County property tax rate (FY 2027, principal residence outside a municipality): $1.1521 per $100 (County Council Resolution 20-1141)
• Tax savings: $50,000 × 0.011521 = ~$576 per year
• Over three years (until next reassessment): ~$1,728 in savings

On larger properties or bigger reductions, the math gets more compelling. Many professional tax appeal services work on a contingency basis — they take 30–50% of the first year's savings — so there's no out-of-pocket cost.

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New Buyers: Does a Purchase Reset Your Assessment?

Yes — sort of. When you purchase a property, SDAT receives a notice of the sale. If your purchase price is significantly above the current assessed value, SDAT will typically reassess the property in the next reassessment cycle using your sale as evidence of market value.

This means if you bought a home that was assessed at $550,000 for $700,000, you should expect the assessed value to move toward $700,000 at the next triennial reassessment. The phase-in and the 10% Homestead cap slow how fast the taxable value can increase, but it will trend upward.

Three things new owners should know:

• You have your own appeal window. If the property transferred to you between January 1 and June 30, you can appeal within 60 days of the transfer, even without an Assessment Notice.
• The Homestead cap doesn't start right away. A new owner isn't eligible for the Homestead Tax Credit in the first full fiscal year of ownership. File the one-time application after closing so it's in place after that.
• Renovated homes can jump fast. If the seller made improvements adding more than $100,000 in value, SDAT reassesses out of cycle and that value isn't phased in. On a flipped home, your taxes can rise within months of closing. I walk through a real example in why property taxes jump after buying a flipped home.

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How Often Is My Home Reassessed in Montgomery County?

Every three years. Maryland divides all properties into three reassessment groups. The specific cycle for your property is on your SDAT record.

Between reassessment years, your assessed value doesn't change unless SDAT receives notification of a permit, subdivision, or other triggering event. Improvements or new construction that add more than $100,000 of value trigger an out-of-cycle reassessment, and that added value is not phased in. You can also receive a supplemental, partial-year tax bill. Smaller improvements, like finishing part of a basement or adding a bathroom, are generally picked up at your next regular reassessment.

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Frequently Asked Questions

How do I appeal my Montgomery County property assessment?

File a Level 1 Supervisor's Appeal within 45 days of your assessment notice. Submit the form to SDAT's Montgomery County office with supporting evidence (comparable sales, condition documentation, appraisal). If unsatisfied, escalate to PTAAB, then Maryland Tax Court.

What is the deadline to appeal my property assessment in Maryland?

45 days from the date printed on your Assessment Notice. If you miss it, you still have options: in the years your property isn't being reassessed, you can file a Petition for Review by the first working day after January 1, which applies to the tax year starting the following July 1. New owners whose property transferred between January 1 and June 30 can also appeal within 60 days of the transfer (SDAT appeal process).

Does a new purchase reset my assessment in Montgomery County?

Not immediately, but SDAT uses sale prices as evidence at the next triennial reassessment. Expect your assessed value to trend toward your purchase price over the next one to two assessment cycles.

How often are homes reassessed in Maryland?

Every three years. Maryland uses a triennial cycle, with one-third of properties reassessed each January.

What is the 10% cap on property tax increases in Maryland?

Maryland's Homestead Tax Credit caps how much the taxable assessment on your primary residence can increase in any one year at 10% in Montgomery County, even if the full reassessment shows a larger jump. This applies to owner-occupied primary residences whose owners have filed the one-time application. New owners aren't eligible in their first full fiscal year of ownership.

Is it worth hiring a property tax appeal professional?

For properties valued over $600K–$700K with a significant overassessment, yes. Most work on contingency (percentage of first-year savings), so there's no upfront cost. For modest savings amounts, filing yourself at Level 1 is straightforward and free.

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Related Resources

• Montgomery County MD Property Tax Rate (2026): What Homeowners Actually Pay
• How to Look Up Montgomery County Real Estate Records
• When Are Montgomery County Real Estate Taxes Due?
• Bought a Flipped Home? Why Your Property Tax Jumped
• The Real Cost of Buying a Home in Maryland

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Wondering if your current assessment is accurate? I can help you pull comparable sales data and evaluate whether an appeal makes sense for your property. Get in touch.

Sources & further reading

The primary sources behind the tax and assessment figures in this post:

• IRS Topic 701 — Sale of Your Home — the capital-gains exclusion rules in the IRS's own words
• Comptroller of Maryland — Maryland state tax rules, forms and withholding on property sales
• Montgomery County Department of Finance — current county tax rates, billing dates and transfer/recordation figures
• SDAT: Assessment Appeal Process — appeal deadlines, the new-owner window and the Petition for Review
• Montgomery County Council Resolution 20-1141 — FY 2027 property tax rates