In St. Mary's County, your yearly property tax is your assessed value divided by 100, times two rates added together: the county's $0.8478 and the state's $0.112. The county kept its rate at $0.8478 per $100 for fiscal 2027 in its final FY2027 budget, and the state rate is 11.2 cents per $100, according to the Maryland Board of Public Works. On a home assessed at $350,000, that's about $3,359 a year.
This guide walks through the math, how Maryland sets your assessment, the Homestead Credit (and the 3% limit St. Mary's uses), the other credits people miss, and what happens to taxes when you buy or sell. Taxes are part of your monthly payment, so they belong in your budget before you pick a price range.
What Is the Property Tax Rate in St. Mary's County?
For fiscal 2027, which runs July 1, 2026 through June 30, 2027, the combined rate on a typical home is $0.9598 per $100 of assessed value. That's the county's $0.8478 plus the state's $0.112. The county rate was the same in fiscal 2026, so if your assessment didn't change, your county tax didn't either.
Two things trip people up. First, the rate is per $100, not per $1,000, so divide your assessment by 100 before you multiply. Second, your bill is based on the assessment the state sets, not on what you paid. Those two numbers can be far apart, especially if you bought recently.
Yearly Tax on a $350,000 Assessment
Fiscal 2027 rates, before any credits
How Do I Estimate the Tax on a Specific Home?
Look up the home's current assessment for free on SDAT Real Property Search, then do the math. Here's the same $350,000 example, step by step:
- $350,000 divided by 100 is 3,500.
- 3,500 times $0.8478 is $2,967.30 in county tax.
- 3,500 times $0.112 is $392.00 in state tax.
- Together that's $3,359.30 a year, or about $280 a month if your lender escrows it.
If you're buying, don't stop at the seller's current bill. Their bill may include a Homestead Credit or another credit that ends when they sell. I use this same math in my PCS buyer checklist and in how much house you can afford.
How Does Maryland Assess My Home?
The Maryland Department of Assessments and Taxation (SDAT) reassesses every property on a three-year cycle, and owners get a notice in late December when their value changes, according to SDAT's homeowner guide. Each year a different third of the state is reassessed.
When your value goes up, the increase is phased in over the next three years. SDAT's own example: a home going from $100,000 to $130,000 is assessed at $110,000, then $120,000, then $130,000. For the group reassessed as of January 1, 2026, St. Mary's County residential values rose 10.5% over three years, compared with 13.2% statewide, according to SDAT's 2026 reassessment report.
Your assessment isn't an appraisal and it isn't what a buyer will pay. It's a mass estimate. My home value guide explains why your SDAT number and your market value often don't match.
What Is the Homestead Tax Credit, and How Much Does It Save Here?
The Homestead Tax Credit limits how much the taxable assessment on your main home can rise each year. The state limit is 10%, and every county can set a lower one for its own portion of the tax, according to SDAT. St. Mary's County's limit is 3%, per the county's FY2027 budget and SDAT's list of local homestead percentages.
The 3% limit applies to the yearly increase in the taxable assessment used for the county portion of your bill, not to your total tax bill. It only matters when your phased-in assessment rises faster than 3% a year. When it does, you're billed on the capped number instead of the full one, and the difference shows up as a credit on your bill.
Example scenario: This is made-up math to show how the cap works, not a real home. Say your taxable assessment was $300,000 and SDAT's new value is $345,000. The $45,000 increase phases in at $15,000 a year.
| Year | Phased-in assessment | County cap (3% a year) | County credit |
|---|---|---|---|
| 1 | $315,000 | $309,000 | about $51 |
| 2 | $330,000 | $318,270 | about $99 |
| 3 | $345,000 | $327,818 | about $146 |
The credit grows each year the market keeps outrunning the cap. Over time, a long-time owner's taxable assessment can sit well below market value. That's one reason a buyer's first bill can be higher than the seller's.
Who Qualifies for the Homestead Credit
Maryland SDAT eligibility rules
- The home is your principal residence
- You live there at least six months of the year, including July 1
- You file the one-time application with SDAT
- Only one property per owner can get it
The application is one time, and the credit stays as long as you own and live in the home. If you move out and rent the home, it no longer meets the principal residence rule, so plan for a higher bill on a rental.
What Other Property Tax Credits Should I Check?
The Homeowners' Property Tax Credit is income based. Combined gross household income can't exceed $60,000, net worth (not counting the home and retirement savings) has to be under $200,000, and the credit only counts taxes on the first $300,000 of assessed value, according to SDAT. You reapply each year by October 1.
Maryland also has a full exemption for veterans with a 100% service-connected disability that's permanent and total, filed on SDAT form EX4B with your DD-214 and VA rating letter. A surviving spouse version exists too. If that rating applies to you, call the local assessment office. They decide who qualifies, not me.
| Credit or exemption | Who runs it | Who may qualify | How to apply |
|---|---|---|---|
| Homestead Tax Credit | Maryland SDAT | Owner-occupants of a principal residence | One-time application with SDAT |
| Homeowners' Property Tax Credit | Maryland SDAT | Households within the income and net worth limits | Apply each year by October 1 |
| 100% disabled veteran exemption | Maryland SDAT, local assessment office | Veterans with a 100% permanent and total service-connected rating | Form EX4B with DD-214 and VA rating letter |
How Are Property Taxes Handled When I Buy or Sell?
Taxes are split at settlement so each side pays for the days they owned the home. Maryland bills run July 1 to June 30. For principal residences on the semiannual plan, the St. Mary's County Treasurer lists the first installment due September 30 and the second by December 31, so who has already paid what depends on your settlement date.
- Selling in August? The bill may not be paid yet, so your share comes out of your proceeds.
- Selling in November? You may have paid the first half already, and the buyer reimburses you for days after settlement.
- Buying? Your lender will usually collect a few months of taxes up front to start your escrow account.
You'll see all of it on your closing disclosure, along with the St. Mary's transfer and recordation taxes. Your settlement company does the exact proration.
Can I Appeal My Assessment If It Looks Too High?
Yes. You have 45 days from the date on your reassessment notice to appeal, according to SDAT's appeal process page. There are three levels, and none of them charge a filing fee:
The Three Levels of a Maryland Assessment Appeal
Maryland SDAT appeal process
- Supervisor's level
An informal hearing, typically about 15 minutes. File within 45 days of your notice. - Property Tax Assessment Appeals Board
File within 30 days of the supervisor's final notice. - Maryland Tax Court
File within 30 days of the board's order. Further appeals go through the courts.
Strong appeals are built on facts: recent sales of truly similar homes nearby, or condition problems the assessor couldn't see from the street. A higher assessment than your neighbor's isn't enough on its own. I can pull comparable sales so you can decide if an appeal is worth your time.
Why Did My Mortgage Payment Go Up If My Rate Didn't?
If your lender escrows taxes and insurance, your payment includes one-twelfth of each yearly bill. When your assessment rises, a credit ends, or insurance goes up, the lender adjusts your payment at the annual escrow review and may ask you to cover a shortage. Read your annual escrow statement so the change doesn't surprise you.
What About Taxes on New Construction?
On a brand-new home, the first tax bill may not reflect the finished house yet. Once SDAT assesses the completed home, the bill goes up. Ask the builder and your lender how they estimated first-year taxes so your budget isn't built on the value of an empty lot. More in new construction vs. resale.
Who Should I Ask About Each Part of My Tax Bill?
- SDAT's St. Mary's County assessment office: your assessment, the Homestead Credit, the disabled veteran exemption and appeals.
- The St. Mary's County Treasurer: your bill, due dates, payment options and anything past due.
- Your lender or loan servicer: escrow, shortages and why your payment changed.
- Your settlement company: the exact tax proration on your closing disclosure.
- A tax professional: deducting property taxes on your income tax return, or the tax side of a rental.
- Me: estimating taxes on a home you're thinking about buying, and comparable sales if you're weighing an appeal.
Knowing who owns each piece saves you phone calls. The assessment office can't tell you why your mortgage payment changed, and your lender can't change your assessment.
What Property Tax Mistakes Should I Avoid?
- Budgeting from the seller's bill. A long-time owner's bill can include years of Homestead Credit savings. Run the math on the full assessment, then treat any credit you qualify for as a bonus.
- Forgetting the Homestead application. The credit isn't automatic. If you never filed, you may be paying on the full phased-in assessment.
- Letting the December notice sit. The 45-day appeal window starts on the date printed on the notice, not the day you open it.
- Missing the income-based credit. The Homeowners' Property Tax Credit has to be filed every year by October 1.
- Assuming a rental keeps the same bill. Once the home isn't your principal residence, the Homestead Credit rules no longer fit it.
A tax bill is easy to fix before you buy and hard to fix after. Ten minutes on SDAT's site before you write an offer is worth it.
What's the Bottom Line?
Multiply the assessment by $0.9598 per $100 for a quick estimate, apply for the Homestead Credit the month you move in, and check the income and veteran credits if they might fit. If you're shopping for a home or getting ready to sell, I'll run the tax numbers on the exact address with you.
Frequently Asked Questions
For fiscal 2027 the county rate is $0.8478 per $100 of assessed value, unchanged from fiscal 2026, and the state adds $0.112. A home assessed at $350,000 owes about $3,359 a year before credits. See the full example in my PCS buyer checklist.
It limits how much the taxable assessment on your main home can go up each year. The state cap is 10%, and counties can set a lower one. It only kicks in when your assessment rises faster than the cap. Ask me how it fits your budget when you start your home search.
St. Mary's County uses a 3% limit for the county portion of your tax, according to the county's FY2027 budget and SDAT's list of local homestead percentages. The state portion uses the statewide 10% limit. My cost to sell guide covers the other taxes at settlement.
It's a one-time application with the Maryland Department of Assessments and Taxation, and the home has to be your principal residence, lived in at least six months of the year, including July 1. Add it to your move-in list from my buyer's guide.
You have 45 days from the date on your reassessment notice to file, according to SDAT. The first level is an informal hearing, and there's no filing fee at any level. I can pull recent comparable sales to help you decide.
Maryland exempts the home of a veteran with a 100% service-connected disability that is permanent and total, filed with SDAT on form EX4B with a DD-214 and the VA rating letter. A surviving spouse exemption also exists. Confirm eligibility with the local assessment office, and see my Pax River relocation guide for more.
Sources: St. Mary's County FY2027 final budget · Maryland Board of Public Works: FY2027 state tax rate · Maryland SDAT: Homestead Tax Credit · Maryland SDAT: local homestead percentages · Maryland SDAT: Homeowners' Property Tax Credit · Maryland SDAT: homeowner's guide to assessments · Maryland SDAT: 2026 reassessment report · Maryland SDAT: assessment appeal process · Maryland SDAT: disabled veteran exemption form · St. Mary's County Treasurer: bill due dates. Checked October 2026; rules and rates can change, so confirm anything that affects your decision.
This article is general real estate information, not legal, lending, tax, or insurance advice. Talk with the right licensed professional about your specific property.
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