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Updated 2025 Tax Year

St. Mary's County
Property Tax Guide

Everything you need to know about property taxes in St. Mary's County, MD. Rates, due dates, exemptions, and how it affects your monthly payment.

10 Official Sources
8 min read
Quick Facts
Tax Rate
Base rate $0.8478 per $100 assessed value (0.85% effective), varies by special taxing districts and location within county
Exemptions
4+ Available
Section 1

How Property Tax Works

St. Mary's County, Maryland operates under a property tax system that serves as the primary funding mechanism for essential county services including education, public safety, infrastructure maintenance, and community programs. The county's property tax system is based on assessed values determined by the State Department of Assessments and Taxation, with taxes calculated using the county's established tax rates.

For the current tax year, St. Mary's County maintains a base property tax rate of $0.8478 per $100 of assessed value, which translates to an effective rate of approximately 0.85%. However, actual tax rates can vary significantly depending on your specific location within the county due to special taxing districts, municipal taxes, and various assessment districts. Property owners in incorporated areas like Leonardtown may be subject to additional municipal taxes, while some areas benefit from special rebates or reduced rates.

The county reassesses all real property on a three-year cycle as mandated by Maryland state law, ensuring that property values reflect current market conditions. Property taxes fund approximately 60% of the county's general fund budget, making it a critical revenue source for maintaining high-quality public services throughout St. Mary's County.

Section 2

What Makes Up Your Tax Bill

ComponentRate (per $100)Description
County General Fund$0.8478Base county operations, services, and administration
Board of EducationIncluded in basePublic school funding (integrated into county rate)
Debt ServiceIncluded in baseBond payments for capital projects
Municipal Tax (Leonardtown)VariesAdditional tax for incorporated areas (offset by county rebates)
Special Assessment DistrictsVariesWater, sewer, or improvement districts where applicable

Fiscal Year: These rates apply to FY 2025 (tax bills due September 30, 2024).

Important Note: The actual tax rate you pay depends on your property's location within St. Mary's County. Properties in special taxing districts, municipal boundaries, or assessment districts may have different effective rates. Some areas receive rebates that reduce the effective tax burden, while others may have additional assessments for specific services or improvements.

Section 3

When Are Property Taxes Due?

For the 2025/2026 tax year in St. Mary's County, property taxes are due in two installments:

Pro tip: If you pay through mortgage escrow, your lender splits these payments across your monthly mortgage. If you pay directly, set calendar reminders to avoid late penalties.
Section 4

Supplemental Tax Bills

Supplemental taxes in St. Mary's County are additional property tax assessments issued when there are changes to property ownership, improvements, or new construction that occur after the annual assessment date but before the end of the tax year. These taxes ensure that property tax obligations are properly allocated based on actual ownership periods and current property values.

Common Triggers:

  • New construction or major renovations completed mid-year
  • Property ownership transfers that reveal previously unassessed improvements
  • Corrections to assessment errors discovered during the tax year
  • Addition of structures, pools, or other taxable improvements

Calculation Method: Supplemental taxes are calculated by determining the difference between the old and new assessed values, applying the current tax rate to that difference, and prorating based on the number of months remaining in the tax year. For example, if a $50,000 addition is completed in January and assessed in March, the supplemental tax would be calculated on the $50,000 increase for the remaining 10 months of the fiscal year.

Example: A property owner completes a $75,000 home addition in December. The supplemental assessment increases the property value by $75,000. With St. Mary's County's rate of $0.8478 per $100, the additional annual tax would be $635.85. Since 7 months remain in the tax year, the supplemental bill would be approximately $371 ($635.85 × 7/12).

Example Calculation

Example 1: $300,000 Home

  • Assessed Value: $300,000
  • Homeowners' Tax Credit Applied: -$2,500 (estimated, requires application)
  • Net Taxable Value: $297,500
  • Annual Tax: $297,500 × $0.008478 = $2,522
  • Monthly Escrow: $210

Example 2: $600,000 Home

  • Assessed Value: $600,000
  • Homeowners' Tax Credit Applied: -$2,500 (estimated, requires application)
  • Homestead Tax Credit Applied: Assessment growth limited to prior year + 10%
  • Net Taxable Value: $597,500
  • Annual Tax: $597,500 × $0.008478 = $5,066
  • Monthly Escrow: $422

Example 3: $1,000,000 Home

  • Assessed Value: $1,000,000
  • Homeowners' Tax Credit Applied: -$2,500 (estimated, requires application)
  • Net Taxable Value: $997,500
  • Annual Tax: $997,500 × $0.008478 = $8,457
  • Monthly Escrow: $705

Important Notes: Tax credits shown require annual application and approval. Homestead Tax Credit limits assessment increases rather than reducing market value. Actual credits may vary based on income and other eligibility factors. Properties in special districts may have different effective rates.

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Section 5

Escrow & Property Taxes

Most mortgage lenders in St. Mary's County require property tax escrow accounts for borrowers with less than 20% down payment, though some lenders mandate escrow regardless of down payment amount. Your lender collects monthly property tax payments along with your mortgage payment and holds these funds in an escrow account to pay your annual property tax bill when due.

Payment Timing: Lenders typically pay St. Mary's County property taxes by the September 30th deadline to avoid penalties. Your escrow account is analyzed annually, usually around the anniversary of your loan closing, to ensure adequate funds are collected. If property taxes increase due to reassessment or rate changes, your monthly escrow payment will be adjusted accordingly.

Escrow Verification: You can verify that your lender has paid your property taxes by checking the St. Mary's County Treasurer's website or calling their office directly. If you discover your taxes haven't been paid by early October, contact your lender immediately to resolve the issue and avoid additional penalties. Property owners remain ultimately responsible for ensuring taxes are paid even when using escrow services.

Escrow Shortages: If your escrow account has insufficient funds due to assessment increases, your lender may pay the shortage and require you to repay it over the following year, increasing your monthly payment. Some lenders offer the option to pay shortages as a lump sum to avoid higher monthly payments.

How HonestCasa Helps
  • Understand whether your escrow is set correctly
  • See how rising taxes will change your monthly payment
  • Plan ahead instead of being surprised by "shortage" letters
Section 6

Frequently Asked Questions

Q: When are property taxes due in St. Mary's County? A: Property taxes for FY 2025 are due September 30, 2024. The county offers a five-business-day grace period. Online payments must be completed by February 24, 2025, and delinquent notices are mailed in late January for unpaid taxes.

Q: What tax credits are available and do they require application? A: Maryland offers several tax credits that require annual application: Homeowners' Tax Credit (income-based), Homestead Tax Credit (limits assessment increases to 10% annually), Veterans' Exemption, and Blind Persons' Credit. None of these are automatic - you must apply through the State Department of Assessments and Taxation.

Q: How does the Homestead Tax Credit work? A: The Homestead Tax Credit caps annual assessment increases at 10% for your primary residence. It doesn't reduce your property's market value but limits how much your taxable assessment can increase each year. You must file an application, and it's not automatic even for longtime homeowners.

Q: How often are properties reassessed in St. Mary's County? A: Maryland law requires property reassessment every three years. St. Mary's County follows this state-mandated cycle, with the most recent countywide reassessment completed in 2023. Interim assessments may occur for new construction or major improvements.

Q: What are the penalties for late property tax payments? A: St. Mary's County charges interest and penalties on delinquent property taxes. After the grace period expires in early October, interest begins accruing monthly. Continued delinquency can result in tax lien certificates being sold to investors, and eventually tax sale proceedings.

Q: Can I pay property taxes online? A: Yes, St. Mary's County offers online property tax payments through their official website. Online payments are accepted until February 24th of the following year. The system accepts electronic checks and credit cards, though credit card payments may incur processing fees.

Q: Why is my tax rate different from my neighbor's? A: Tax rates in St. Mary's County can vary based on special taxing districts, municipal boundaries, and special assessment areas. Properties in Leonardtown face additional municipal taxes but may receive county rebates. Some areas have special districts for water, sewer, or community improvements that add to the base rate.

Q: How do I appeal my property assessment? A: Assessment appeals must be filed with the Maryland Tax Court within 30 days of receiving your assessment notice. You can also request an informal review with the local assessor's office before filing a formal appeal. Appeals should include evidence such as recent comparable sales, appraisals, or documentation of property condition issues.

Q: What happens if I buy or sell property mid-year? A: Property taxes in Maryland are prorated based on the ownership transfer date. The settlement attorney typically handles the proration calculation at closing, ensuring each party pays taxes for their period of ownership. Supplemental bills may be issued if assessments change after the transfer.

Q: Are there property tax relief programs for seniors or disabled residents? A: Maryland offers several property tax relief programs including the Homeowners' Tax Credit (income-based), enhanced credits for seniors and disabled residents, and the Property Tax Deferral Program for qualifying elderly homeowners. All programs require application and income verification through the State Department of Assessments and Taxation.

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