Montgomery County Maryland property tax assessment: how it works and how to fight it

Last updated 2026-07-09

How does Maryland assess property in Montgomery County?

Maryland's State Department of Assessments and Taxation (SDAT) values your property, not Montgomery County. That surprises people who moved from states where a county assessor does the work. SDAT employs field supervisors who value every property in the state on a 3-year rotating schedule, called a triennial cycle. Montgomery County is one geographic supervisory district inside that system. ^[1]

SDAT uses a mass appraisal model. Nobody walks through your home every three years. Assessors study recent sales of comparable properties, adjust for size, age, condition, and location, and land on an estimated market value for your parcel. That number is your "full cash value" for assessment purposes.

Under Maryland law, your assessed value is supposed to equal 100 percent of market value. ^[2] In practice, assessed values drift from real market value between cycles. That gap is exactly what you exploit on appeal.

Once SDAT sets your full cash value, any increase over your last assessment gets phased in over the three years of the next cycle. Say your old value was $400,000 and the new value is $520,000. You don't jump to $520,000 overnight. You climb in three roughly equal steps across tax years one, two, and three. That phase-in cap lives in Maryland Code, Tax-Property Article Section 8-104. ^[3]

What is the triennial reassessment cycle and when does it affect your bill?

Maryland splits all taxable real property into three groups, and reassesses one group each year. Montgomery County parcels fall across all three groups depending on your supervisory area. Look up your parcel on SDAT's Real Property Search and it tells you your next reassessment year. ^[4]

Here is how the cycle runs in practice:

Phase	What Happens	Timing
SDAT mails notice	You receive your new assessed value	Late December / early January
Appeal window opens	45-day period begins the day after notice date	January or February
Appeal deadline	Petition for Review must be filed	45 days after notice date
Supervisor conference	Informal review with SDAT supervisor	Usually within 60-90 days of filing
Property Tax Assessment Appeal Board (PTAAB)	Formal first-level appeal if dissatisfied	Filed within 30 days of supervisor decision
Maryland Tax Court	Second formal appeal if still dissatisfied	Filed within 30 days of PTAAB decision

The 45-day deadline is hard. Miss it and you wait three years for your next shot, unless you can show cause. And don't assume the postmark starts your clock. SDAT counts from the date printed on the notice. ^[5]

Own a home in a neighboring jurisdiction and want to see how the cycles differ? The montgomery county property tax overview lays Maryland and Virginia counties side by side.

What tax rates apply once your assessment is set?

Your tax bill is your assessed value times a tax rate. In Montgomery County you pay at least two rates: the state rate and the county rate. Some areas add special taxing district surcharges for things like fire districts or development areas.

For fiscal year 2025, Maryland's state real property tax rate is $0.112 per $100 of assessed value. ^[6] Montgomery County's FY2025 real property rate is $0.9787 per $100. ^[7] Stack those and a home assessed at $600,000 carries a combined county-plus-state burden of roughly $6,540 a year, before any exemptions or credits.

Here's what most people miss. Cutting your assessment by $30,000 saves you about $330 a year in combined county and state tax. Over the three-year cycle that's close to $1,000. That math makes a DIY appeal worth the afternoon it takes.

Montgomery County cannot change your assessed value. Only SDAT can. The county sets rates and mails bills, but every assessment dispute runs through the SDAT appeal chain.

How do you read your SDAT assessment notice?

Your notice arrives as a printed letter from SDAT, usually late December or the first days of January. It shows four numbers: your old full cash value, your new full cash value, your old phased-in value, and your new phased-in value for year one of the cycle.

The full cash value is the number you fight on appeal. The phased-in value is what actually gets taxed in year one.

The notice also lists your property's physical description: square footage, bedroom and bathroom counts, lot size, year built, any outbuildings. Read this part slowly. Errors here, like a bedroom that doesn't exist or a "finished" basement that's really unfinished storage, are legitimate appeal grounds and among the easiest to win. They're factual, not a matter of opinion.

The notice states the appeal deadline flat out. It also explains how to request an informal supervisor conference, which is your first step. You can appeal online through Maryland's appeal system or mail a written petition. ^[5]

Want to see how assessed value flows into your actual tax bill? The property assessment value guide walks the mechanics in plain terms.

What grounds can you use to appeal a Montgomery County assessment?

Maryland law gives you three valid bases for a residential appeal. ^[2]

First: the assessed value tops the property's actual market value. This is the common argument, and the one you back with recent comparable sales.

Second: the property isn't assessed uniformly against similar nearby homes. If your neighbor's identical townhouse is assessed 15 percent lower, that's a uniformity argument.

Third: the physical description on file is wrong. Wrong square footage, wrong bedroom count, wrong condition grade. These are often the fastest wins.

The comparables argument takes homework. Pull three to five recent arms-length sales of homes like yours, within roughly a half mile and the last 12 months. "Similar" means within 15 percent of your gross living area, the same construction type, the same neighborhood. Get them from SDAT's own sales data or public MLS records. If those sales consistently point below SDAT's number, you have a case.

You don't need an appraisal to appeal. An appraisal helps, but it costs $300 to $600. For most residential appeals, a tidy set of comps from SDAT's own database wins at the supervisor conference and often at PTAAB too. Save the appraisal money for Maryland Tax Court, if you ever get there.

For how to find and present comparable sales, the evidence and comps section has a full walkthrough.

How do you file a property tax appeal in Montgomery County step by step?

Step one: decide if it's worth your time. Look up three to five recent sales of comparable homes. If they say your property is overvalued by $15,000 to $20,000 or more, the tax savings justify the work.

Step two: file your Petition for Review before the 45-day deadline. File online through SDAT's online services portal, by mail to the SDAT Montgomery County Supervisory Office, or in person. The petition is short: your name, address, parcel account number, and the value you think is right. You don't need your evidence package yet. ^[5]

Step three: prep for the supervisor conference. This is an informal meeting with the SDAT area supervisor. Bring printed comps, your property record card (pulled from SDAT's site), photos of any condition problems, and any factual errors you found. Be polite. Supervisors have real discretion, and plenty of reductions happen right here.

Step four: if the supervisor won't cut the value enough, you have 30 days to file with the Property Tax Assessment Appeal Board (PTAAB) for Montgomery County. PTAAB hearings run at county offices and feel more formal, but you still represent yourself with no special credential.

Step five: lose at PTAAB and you can go to Maryland Tax Court within 30 days of the PTAAB decision. It's a real court, but the procedures stay relatively informal. Most homeowners stop at PTAAB.

Want a structured package that covers all three levels? TaxFightBack's DIY appeal kit is built for Maryland, with a comp worksheet and a hearing prep checklist, so you keep every dollar of whatever you win.

Curious how other high-value places run appeals? See loudoun county property tax or philadelphia property tax.

What property tax exemptions and credits are available in Montgomery County?

Maryland and Montgomery County both offer credits and exemptions that cut your bill independent of any appeal.

Homestead Tax Credit: this is Maryland's main residential protection. Once you establish your primary residence and apply, your taxable assessment can rise no more than 10 percent a year for state purposes and no more than the county's own cap for county purposes. Montgomery County's Homestead cap is 10 percent. ^[8] It does not lower your assessed value. It caps how fast the taxable portion grows. You apply once, and it renews automatically after approval. Never applied? You may have left money on the table for years.

Homeowners' Tax Credit: Maryland's circuit-breaker credit limits property tax to a share of your household income on a sliding scale. For 2025 it's open to homeowners with combined household income up to $60,000, and the application deadline is September 1 each year. ^[9] This credit stays badly underused. Households earning between $30,000 and $60,000 should always apply.

Seniors and persons with disabilities: Maryland Code Tax-Property Article Section 9-104 provides an assessment freeze for homeowners 65 and older who meet income and residency rules. Montgomery County also runs a supplemental senior credit. ^[10]

Disabled veterans and surviving spouses: qualifying disabled veterans and their surviving spouses may receive a full exemption from real property tax under Maryland Tax-Property Article Section 7-208. ^[12]

Apply for every credit you qualify for before you appeal. A credit stacks on top of an appeal reduction. They aren't mutually exclusive.

How does Montgomery County compare to Nassau County property tax assessments?

People often research Montgomery County, Maryland and Nassau County, New York together. Both are high-income suburbs with assessment systems that get picked apart in public.

The two work very differently. Maryland's assessment is a state job, run by SDAT the same way across all 24 jurisdictions. Nassau County runs its own county assessment operation and has a long record of mass grievance filings. Part of the reason: Nassau historically assessed at a fraction of market value, and applied that ratio inconsistently, which produced big inequities between similar homes. A 2017 Newsday investigation and later academic work found that lower-value Nassau homes were systematically over-assessed relative to higher-value homes. ^[11]

Maryland's state-run system has fewer of those structural ratio problems because SDAT aims at 100 percent of market value directly, and the Homestead Credit softens phase-in shock. But SDAT still makes mistakes on individual properties, and a 3-year-old assessed value can sit well above a currently falling market.

The filing mechanics diverge sharply. Nassau uses a formal Grievance Day deadline in late May. Maryland uses the 45-day notice window. If you're working both jurisdictions at once, don't cross the deadlines.

What is SDAT's real property database and how do you use it to build your case?

SDAT's Real Property Search is your best free tool. Every property in Maryland has a public record card showing the exact data SDAT used on your assessment: square footage, bedroom and bathroom counts, finished basement area, garage type, deck, condition grade, and recent neighborhood sales.

Start with your own record card and check every physical detail. Wrong gross living area is common on older records. A 200-square-foot error at a $250-per-square-foot basis adds $50,000 to your assessed value, and fixing it costs nothing but a letter.

Next, use the sales tool to find recent comparable sales. Filter by property type, sale date, and area. Drop the results into a spreadsheet. Calculate the median price per square foot from at least five sales in the last 12 months. Compare that to the price per square foot baked into your assessment. If your assessed value runs 10 to 15 percent above that median, you have a credible case.

For a deeper guide on reading a database like this in any jurisdiction, see the property tax records and property tax lookup articles.

What are the key deadlines for Montgomery County property tax appeals in 2025 and 2026?

These are the dates that decide whether you can act or have to wait three years.

Event	Deadline	Authority
Assessment notices mailed	Late December / early January	SDAT annual cycle
Petition for Review deadline	45 days after notice date	Maryland Tax-Property Art. § 14-502
Homestead Credit application (new owners)	Within 180 days of sale	SDAT
Homeowners' Tax Credit application	September 1 annually	Maryland Tax-Property Art. § 9-104
PTAAB appeal after supervisor decision	30 days after supervisor letter	SDAT regulations
Maryland Tax Court appeal	30 days after PTAAB decision	Maryland Tax Court rules

The 45-day Petition for Review deadline kills most DIY appeals before they start. People read the notice in January, set it on the counter, and miss it by a week. Put the deadline on your calendar the moment the notice lands. Maryland Tax-Property Article Section 14-502 states it plainly: "A complaint shall be filed within 45 days after the date of the notice." ^[5]

One more date trap. A notice dated January 1 expires around February 14. A notice dated December 28 closes around February 11. Count from the notice date, never the day you opened the envelope.

Should you hire a tax appeal firm or do it yourself in Maryland?

Contingency firms usually take 25 to 40 percent of the tax savings they produce, often with a one-year minimum fee. On a $500 annual reduction, that's $125 to $200 to the firm. Across the 3-year cycle you'd save $1,500, and the firm skims $375 to $600 off the top.

The Maryland residential process at the supervisor conference and PTAAB level doesn't require an attorney or licensed rep. Homeowners appear pro se all the time. PTAAB members are appointed civilians, not judges, and the hearings are built to be usable by regular people. Homeowners who show up with organized comparable sales tend to win reductions at rates close to represented petitioners at the first two levels, a pattern SDAT's own appeal design assumes.

Hiring a firm makes sense in three cases: the property is commercial or income-producing (valuation gets complicated), the assessed value runs into the millions (the dollar savings justify the fee), or you flatly won't do the research yourself. For a typical Montgomery County single-family home, DIY is the rational call.

Want structure without paying contingency? TaxFightBack's appeal kit walks you through SDAT's database, comp selection, and how to present at a PTAAB hearing, so you keep every dollar of your reduction.

To compare how other high-stakes places handle self-representation, the clark county property tax guide covers Nevada's appeal board, and bexar county property taxes covers Texas's ARB process.

What happens after you win a Montgomery County property tax appeal?

If SDAT cuts your assessed value, the reduction applies to the full three-year cycle going forward, and you get a corrected tax bill. Already paid at the higher number? Montgomery County issues a refund or credits your next bill.

The reduction resets your phased-in value too. Say you were phasing in from $400,000 to $520,000 over three years and you win a reduction to $460,000. Your new phase-in runs from your prior phased-in value up to $460,000. The math nicks your first-year savings a bit, but over the cycle you capture the full difference.

Keep your paperwork. When the next triennial notice arrives in three years, pull out this cycle's comps. Some stay useful as baseline references. Some assessors treat a prior successful appeal as a reason to run conservative next cycle, though nobody guarantees that.

Last thing: recheck your Homestead Credit status after a reduction. A cut does not cancel the credit, and the credit applies to your new lower base. Both protections stack.

Frequently asked questions

How often does Montgomery County reassess property values in Maryland?

SDAT reassesses every property in Maryland on a 3-year triennial cycle. Your specific reassessment year depends on which of the three supervisory groups your parcel falls in. Check your next reassessment year by looking up your parcel on SDAT's Real Property Search. Assessment notices usually mail in late December or early January of your reassessment year.

What is the deadline to appeal my Montgomery County Maryland property tax assessment?

You have 45 days from the date printed on your SDAT notice to file a Petition for Review. Maryland Tax-Property Article Section 14-502 sets it. Miss it and you generally wait three years for the next reassessment. File online through SDAT's portal, by mail, or in person at the Montgomery County supervisory office. Count from the notice date, not the postmark.

What percentage of market value does Maryland assess property at?

Maryland law requires assessed value to equal 100 percent of full cash value, meaning market value. Any increase over the prior assessment then phases in over the three-year cycle in roughly equal annual steps. The taxable phased-in value in a given year is often lower than the full assessed value if you're still inside a phase-in period.

What is the Montgomery County property tax rate for 2025?

For FY2025, Montgomery County's real property tax rate is $0.9787 per $100 of assessed value. The Maryland state rate adds $0.112 per $100. Combined, a home assessed at $600,000 carries roughly $6,540 in county and state property tax before credits or exemptions. Some special taxing districts inside the county add surcharges on top.

Can I appeal my assessment if I disagree with the comparable sales SDAT used?

Yes. At the supervisor conference and PTAAB hearing you can present your own comparable sales from SDAT's sales database or MLS records. Use arms-length sales of similar homes within roughly a half mile and the last 12 months. If your comps consistently support a lower value than SDAT's, that's a valid market-value argument under Maryland Tax-Property Article Section 14-503.

What is the Maryland Homestead Tax Credit and how does it reduce my bill?

The Homestead Tax Credit caps how fast your taxable assessed value can rise each year. For Montgomery County, the cap is 10 percent annually for both county and state tax. It applies only to your primary residence after a one-time application. It does not reduce your assessed value; it limits taxable growth. Apply through SDAT. Once approved, it renews automatically each year.

Do I need a lawyer or appraiser to appeal my Montgomery County assessment?

No. Maryland's supervisor conference and PTAAB hearings are built for self-representation. You need organized comparable sales, your property record card, and proof of any factual errors. A licensed appraisal helps at Maryland Tax Court but usually costs $300 to $600. Most residential appeals settle at PTAAB on comps alone, without professional representation.

What property tax exemptions are available to seniors in Montgomery County?

Maryland Tax-Property Article Section 9-104 provides an assessment freeze for homeowners 65 and older who meet income limits, keeping their taxable assessment from rising even as market value climbs. Montgomery County also runs a supplemental senior tax credit with its own income thresholds. Applications go through SDAT and the Montgomery County Department of Finance respectively. Check both; you can qualify for both at once.

How does the Nassau County property tax assessment process differ from Montgomery County?

Nassau County, New York runs its own county assessment office and historically assessed at a fraction of market value rather than Maryland's 100 percent. Nassau's appeal uses a formal Grievance Day deadline in late May, while Montgomery County follows Maryland's 45-day notice window after the SDAT mailing. The evidence is similar (comparable sales) but the filing procedures, deadlines, and statutes are completely different.

Where do I file a property tax appeal for Montgomery County Maryland?

File your Petition for Review with SDAT, not with Montgomery County government. File online through SDAT's portal, by mail to SDAT's Montgomery County Supervisory Office, or in person. If you escalate to PTAAB, hearings run at the Montgomery County PTAAB office. Maryland Tax Court filings go to the Maryland Tax Court in Annapolis.

What if I find a factual error in my SDAT property record, like wrong square footage?

Factual errors in the record are among the most straightforward appeal grounds. If SDAT shows 2,400 square feet but your home is 2,100, that inflated figure directly inflates your assessed value. Document the gap with building permit records, a floor plan, or a licensed measurement. Raise it at the supervisor conference. Many supervisors correct clear factual errors on the spot.

Can I appeal my property tax assessment in Montgomery County if my property value has dropped?

Yes, and it's common after market corrections. If recent comparable sales show your home's market value sits below SDAT's assessed full cash value, you have a valid appeal no matter which way values moved. Gather three to five recent sales of comparable homes from SDAT's sales database, calculate the implied market value, and file your Petition for Review before the 45-day deadline.

What happens to my assessment appeal if I sell my house before the hearing?

In Maryland, a pending assessment appeal generally does not transfer automatically to a new owner. If you sell before the hearing, check the purchase contract for who has the right to pursue any reduction and who keeps a resulting refund. Sellers sometimes assign appeal rights at closing. It's negotiable, so raise it with your settlement attorney.

How do I know what my Montgomery County property is actually worth for appeal purposes?

Start with SDAT's Real Property Search to find recent arms-length sales of comparable homes in your neighborhood. Filter for similar size, age, and construction type. Calculate the price per square foot from those sales and apply it to your home's actual living area. If the result sits materially below SDAT's full cash value, you have a credible market-value argument. An appraisal gives a stronger formal opinion but isn't required at the supervisor conference.

Sources

1. Maryland State Department of Assessments and Taxation (SDAT) - Real Property: SDAT, not county government, administers property assessments across all Maryland jurisdictions including Montgomery County on a triennial cycle.
2. Maryland Code, Tax-Property Article Section 8-101 (Maryland General Assembly): Maryland law requires assessed value to equal 100 percent of a property's full cash value (market value) and identifies the valid grounds for appeal.
3. Maryland Code, Tax-Property Article Section 8-104 (Maryland General Assembly): Assessment increases are phased in over the three years of the new triennial cycle in equal annual increments.
4. SDAT Real Property Search - Maryland State Department of Assessments and Taxation: SDAT's public database shows each parcel's next reassessment year, property record card details, and comparable sales data.
5. Maryland Code, Tax-Property Article Section 14-502 (Maryland General Assembly): The statute states: 'A complaint shall be filed within 45 days after the date of the notice.' This is the hard deadline for filing a Petition for Review.
6. Maryland State Department of Assessments and Taxation - Tax Rates: The Maryland state real property tax rate for FY2025 is $0.112 per $100 of assessed value.
7. Montgomery County Maryland - Department of Finance: Montgomery County's real property tax rate for FY2025 is $0.9787 per $100 of assessed value.
8. SDAT Homestead Tax Credit - Maryland State Department of Assessments and Taxation: Montgomery County's Homestead Credit caps taxable assessment growth at 10 percent per year for the county portion after a one-time application by the homeowner.
9. Maryland Homeowners' Tax Credit Program - SDAT: The Maryland Homeowners' Tax Credit (circuit-breaker) is available for 2025 to households with income up to $60,000, with a September 1 annual application deadline.
10. Maryland Code, Tax-Property Article Section 9-104 (Maryland General Assembly): Homeowners 65 and older meeting income and residency requirements qualify for an assessment freeze under Maryland's senior credit program.
11. Lincoln Institute of Land Policy: Academic and investigative work documented that lower-value homes in Nassau County, New York were systematically over-assessed relative to higher-value homes, a structural inequity less common in Maryland's state-administered 100-percent-of-market-value system.
12. Maryland Code, Tax-Property Article Section 7-208 (Maryland General Assembly): Qualifying disabled veterans and their surviving spouses may receive a full exemption from real property tax in Maryland.