How to Look Up Your Maryland Political Subdivision Code

Your Maryland political subdivision code is the four-digit number that identifies the county or municipality where you live so the Comptroller can route your local income tax to the right jurisdiction. You enter it on your Maryland resident return, and you can find the full list in the instructions for Form 502 and on the current Form MW507 that your employer uses for withholding.¹

What the Code Is and Where It Appears

Maryland is one of the few states where every county and Baltimore City levies a local income tax on top of the state income tax, and each jurisdiction sets its own rate. The Comptroller’s office uses the political subdivision code to send your local tax dollars to the correct government.

You will run into the code in two main places:

Form 502, the resident income tax return. You enter the name of your political subdivision and its four-digit code so the state knows where to credit your local tax.
Form MW507, the employee withholding certificate. When you start a job, you tell your employer your county of residence on MW507. That entry determines the local withholding rate applied to every paycheck.¹

The code is tied to where you lived on the last day of the tax year, not where you worked or owned property. If you moved during the year, the subdivision you list is the one you resided in on December 31.

How to Look Up Your Code

The Comptroller of Maryland publishes the current list of political subdivision codes and the local tax rate for each jurisdiction. The most reliable sources are:

The instructions booklet for Form 502 for the year you are filing. Each edition includes the full table of counties, Baltimore City, and incorporated municipalities with their four-digit codes.
The current Form MW507 and its accompanying withholding guide, which list each jurisdiction’s code alongside the local income tax rate the employer must apply.¹

Use the version that matches the tax year you are filing for. Rates and, occasionally, codes change; the wrong year’s booklet can send you to a rate that no longer applies.

If you are unsure which subdivision covers your address, start with the county. Every Maryland address sits in a county (or in Baltimore City, which is treated as its own subdivision for tax purposes). Some incorporated towns and cities have their own separate codes as well, so check whether your street address falls inside municipal boundaries before defaulting to the county code.

Why the Right Code Matters

Getting this wrong has real consequences. If you list the wrong subdivision, your local tax payment may go to the wrong county, creating a shortfall that could trigger a balance-due notice from the Comptroller. Because local rates differ, an incorrect entry can also under- or overstate the local tax you actually owe, which affects your refund or the balance due at filing time.

The same care applies to MW507. If you list a county with a lower rate than the one you actually live in, too little local tax comes out of your paycheck all year, and you make it up at filing. Listing a higher-rate jurisdiction has the reverse effect: more withheld each pay period, then adjusted at the return.

If You Work in Maryland but Live Elsewhere

Nonresidents who work in Maryland face a different rule. They are generally liable for local tax at the rate of the Maryland county where they work, rather than a home-county rate, unless a reciprocity exemption applies.

Pennsylvania residents working in Maryland are the most common example. Depending on which Pennsylvania jurisdiction you live in, you may qualify for a local tax exemption on your Maryland earnings. The MW507 instructions explain how to claim it. If you live in a state without a reciprocity agreement covering local tax, expect Maryland local tax to be withheld at the rate for the county where your employer is located.

What “Political Subdivision” Means in Maryland

The phrase can be confusing because Maryland uses it in more than one context. For income tax purposes, a political subdivision is the county or Baltimore City to which your local tax is credited, and in some cases an incorporated municipality with its own code. Under the Maryland Code’s Local Government Article, the term is broader: it covers counties, municipalities, and special districts, each with its own legal framework.²

A few distinctions are useful when you are trying to figure out which name to look up:

Counties

Maryland has charter counties, which operate under Article XI-A of the state constitution and adopt their own charters with an elected county council,³ and code counties, which have not adopted a charter but can enact their own public local laws under Article XI-F.⁴ For tax purposes, this internal distinction does not change how you file: every county has one subdivision code.

Municipalities

Incorporated municipalities have their own home rule framework under Article XI-E of the constitution.⁵ Some Maryland municipalities have their own political subdivision code separate from the surrounding county, so residents of incorporated towns should check the Form 502 instructions for a municipal listing before using the county code.

Special Districts

Special districts are independent units of government created for a narrow purpose, such as fire protection, water supply, or sanitary services, and they operate under the Local Government Article and the Special Taxing District Act.⁶ They may levy assessments within their boundaries, but they are not the “political subdivision” you enter on your Maryland income tax return. Living in a special taxing district does not change the county or municipal code you use on Form 502.

Don’t Confuse the State Code with Federal Identifiers

Maryland’s four-digit political subdivision code is a state tax identifier and is separate from the federal codes assigned to the same jurisdictions. The Census Bureau maintains American National Standards Institute (ANSI) codes, formerly called Federal Information Processing Series (FIPS) codes, that give numeric identifiers to states, counties, county subdivisions, and places for federal data purposes.⁷

Those federal codes appear in grant applications, demographic research, and federal reporting, but they are not what Maryland asks for on Form 502 or MW507. If you are filing a Maryland income tax return, use the four-digit code from the Comptroller’s forms and instructions, not a Census Bureau identifier.

Where to Confirm the Current Code and Rate

Before filing, cross-check two things against the Comptroller’s current-year materials:

The four-digit code for your subdivision matches the one printed for your county or municipality in the Form 502 instructions.
The local tax rate the Comptroller has published for that subdivision matches the rate applied on your return or by your employer’s withholding.

The Maryland General Assembly’s website provides a searchable interface to the full Maryland Code if you want to read the underlying statutes,⁸ and Justia maintains the current text of the Local Government Article with a browsable table of contents.² For the code itself and the matching local rate, the Comptroller’s forms and withholding guides are the source that governs what you put on your return.

1
Comptroller of Maryland. 2026 Maryland Form MW507
2
Justia. 2025 Maryland Code – Local Government
3
Maryland State Archives. Maryland Constitution – Article XI-A – Local Legislation
4
Maryland State Archives. Maryland Constitution – Article XI-F – Home Rule for Code Counties
5
New York Codes, Rules and Regulations. Maryland Constitution, Art. 11-E, Section 6 – Home Rule Charters
6
United States Census Bureau. Are There Special Districts in Your Hometown?
7
United States Census Bureau. American National Standards Institute (ANSI), Federal Information Processing Series (FIPS), and Other Standardized Geographic Codes
8
Maryland General Assembly. Laws – Statutes – Maryland