Business Income Tax Filing Information" (2024)

Business taxpayers will find important information about filing Business Income Tax for Corporations, Pass-through entities and sole proprietorships. Follow the links below for detailed information.

Quick Links

  • Business Electronic Filing | bFile
  • Business Income Tax Forms and Instructions
  • Employer Withholding Tables
  • Employer Withholding Guide
  • Business Tax Credits

Filing the Corporation Income Tax Return

Every Maryland corporation must file a corporation income tax return, using Form 500, even if the corporation has no taxable income or is inactive.

Corporation income tax returns can be filed electronically, using approved software. Talk to your software provider about electronic filing options.

Every other corporation that is subject to Maryland income tax law and has income or losses attributable to sources within Maryland must also file Form 500.

Corporations operating in Maryland and in one or more other states are subject to Maryland income tax if their Maryland activity exceeds the provisions for federal protection from state taxation. 15 U.S.C. Section 381 (P.L. 86-272) of the Interstate Commerce Act (P.L. 86-272) prescribes the extent of business activity required before states may impose income taxes.

A Multi-state corporation that operates in Maryland but is not subject to the Maryland income tax is not required to file, although a return reflecting an apportionment factor of zero may be filed for record purposes. We cannot accept letters sent in lieu of filing.

All financial institutions formerly subject to the financial institution franchise tax are subject to corporation income tax and have special apportionment rules. For more information, see Regulation 03.04.08 on COMAR Online.


Remember to enter your federal employer identification number (FEIN) on the Maryland corporation tax return and other forms.

Use Activity Code

Be sure to enter the business activity code number on Form 500.


Indicate the following on all correspondence and payments:

  • Corporate name
  • FEIN
  • Tax type
  • Tax year

Every corporation that reasonably expects its Maryland taxable income to develop a tax in excess of $1,000 for the tax year or period must make estimated income tax payments with Form 500D-Maryland Declaration of Estimated Corporation Income Tax.

If the corporation is required to make multiple payments it will use Form 500D for each of the additional payments. The Comptroller of Maryland has discontinued the use of Form 500DP.

Do not use this form to remit estimated tax for Form 510 or to remit employer withholding tax.

The total Maryland estimated tax payments must be at least 90% of the tax developed for the current tax year or 110% of the tax developed for the prior tax year. At least 25% of the total estimated tax must be remitted by each of the four installment due dates.

The annualization method for calculating estimated tax is not permitted for corporations. In the case of a short tax period the total estimated tax payment required is the same as for a regular tax year: 90% of the tax developed for the current (short) tax year or 110% of the tax developed for the prior tax year. The minimum estimated tax for each of the installment due dates is the total estimated tax required divided by the number of installment due dates occurring during the short tax year.

Computing the Apportionment Factor

Multi-state corporations are corporations that operate in more than one state and beyond the protection of 15 U.S.C. Section 381 (P.L. 86-272) of the Interstate Commerce Act. Multi-state corporations operating in Maryland as a unitary business must allocate income using an apportionment formula.

Unistate corporations are those that operate in only one state, or operate in more than one state but the extent of the activity in the other states is within the protection of 15 U.S.C. Section 381 (P.L. 86-272). Unistate corporations subject to the Maryland income tax law may not apportion income.

Allocation means the assignment of income to a particular state. Apportionment means the allocation of income among the states by the use of a formula containing apportionment factors. For more information regarding the computation of apportionment factors, see Administrative Release No. 2: Interstate Commerce Act - Domestic and Foreign Corporations - Nexus Requirements - Apportionment of Corporate Net Income and Maryland Tax Regulation 03.04.03.

The Maryland corporation income tax applies to every Maryland corporation and every other corporation that has a nexus with Maryland. Nexus indicates a taxable connection between a corporation and a taxing authority. If a corporation conducts business activity within Maryland and exceeds the provisions of U.S.C.A. Title15, Section 381 of the Interstate Commerce Tax Act (P.L. 86-272), it has a nexus and must file a corporation income tax return, using Form 500.

The following list includes some in-state activities which generally create nexus and are outside the protection of U.S.C.A. Title 15 Section 381 (P.L. 86-272):

  • Maintaining a business location in Maryland, including any kind of office.
  • Ownership or use of property in Maryland, real or personal, whether the property is rented office space or equipment used in the manufacture and distribution of goods.
  • Employees soliciting and accepting orders in Maryland.
  • Installation or assembly of the corporation's product.
  • Maintaining a stock of inventory in a public warehouse or placement of the corporation's inventory in the hands of a distributor or other non-employee representative.
  • Sales persons making collections on regular or delinquent accounts.
  • Technical assistance and training with Maryland offered by corporate personnel to purchasers or users of corporate products after the sale.
  • Corporate personnel repairing or replacing faulty or damaged goods.
  • Mobile stores in Maryland (such as trucks with driver-salesmen) from which direct sales are made.

For more information, see Administrative Release No. 2, Interstate Commerce Tax Act - Domestic and Foreign Corporations - Nexus Requirements - Apportionment of Corporate Net Income

When to File

Form 500 must be filed by the 15th day of the fourth month following the close of the taxable year or period, or by the original due date required for filing the federal return.

Corporations and organizations that are allowed later due dates for federal returns under the Internal Revenue Code are allowed the same due date for Maryland income tax returns.

If you are unable to file Form 500 by the due date, you can request a filing extension using Form 500E, Application for Extension of Time to File Corporation Income Tax Return. You can request an extension online if you have previously filed Form 500 and have no estimated balance due on Line 5 of Form 500E.

Pass-through entities unable to file Form 510 by the due date can request a filing extension using Form 510E, Application for Extension of Time to File Pass-Through Entity Income Tax Return. You can request an extension online if you have previously filed Form 510 and have no estimated balance due on Line 5 of Form 510E.

A seven-month extension can be granted for corporations using Form 500E and S corporations using Form 510E, Application for Extension of Time to File Pass-Through Entity Income Tax Return. A six-month extension can be granted for partnerships, limited liability companies and business trusts using Form 510E. In no case can an extension be granted for more than seven months beyond the original due date.

The application extends only the time allowed to file the annual income tax return and not the time allowed to pay the tax.

A request for an extension of time to file will be automatically granted and will not be acknowledged, provided that:

  • The application is properly filed and submitted by the 15th day of the fourth month following the close of the tax year or period, or by the original due date required for filing of the federal return; and
  • Full payment of any balance due is submitted with the application.

For more information about corporation income tax extensions, see Administrative Release No. 4, Extension of Time for Filing Maryland Individual, Corporation, Partnership, Limited Liability Company, Fiduciary Income Tax Returns, and Estate Tax Returns.

Pass-Through Entities

Sole Proprietorships

For federal purposes sole proprietors file Schedule C, Profit or loss from Business with their personal tax return Form 1040. Sole proprietor farmers file Schedule F, Profit or Loss from Farming. If you are a sole proprietor in Maryland you would file the same as an individual using individual using Form 502. Your net profit or less is combined on the return with your other income and deductions and taxed using individual tax rates.

Sole proprietors generally do not have taxes withheld from their income so they usually make quarterly estimated tax payments. The Maryland form to submit quarterly estimated tax payments is Form PV.

Filing information for sole proprietors may be found under Sole Proprietorshipsor in the Filing Information section under Individuals Income Tax section. For federal information on sole proprietors see IRS web site.

Business Income Tax Forms

  • 2024 Income Tax Forms
  • 2023 Income Tax Forms - current year
  • 2022 Income Tax Forms
  • 2021 Income Tax Forms
  • 2020 Income Tax Forms

File Yourself!

There are several ways you can file your business income tax returns on paper or electronically. Please review the links at the bottom of the page, and choose the filing method that best fits your needs.

...Or You Can Use Independent Computer Software Products

You can file both your Maryland and federal tax returns online using approved software on your personal computer.

...Or You Can Use a Professional Tax Preparer

You can choose among a host of professional tax preparers in Maryland who can file your return electronically for you. While we cannot endorse any specific professional, we offer a list of e-file providers for businesses for your convenience.

County Abbreviation
Allegany AL
Anne Arundel AA
Baltimore County BL
Baltimore City BC
Calvert CV
Caroline CL
Carroll CR
Cecil CC
Charles CH
Dorchester DR
Frederick FR
Garrett GR
Harford HR
Howard HW
Kent KN
Montgomery MG
Prince George's PG
Queen Anne's QA
St. Mary's SM
Somerset SS
Talbot TB
Washington WH
Wicomico WC
Worcester WR

Electronic filing is the fastest way to file your business tax return. Electronic filing also allows you to pay your business taxes by direct debit. There are several ways you can file your business tax returns and reports online.

File Electronically

You may use bfile to file Withholding Reconciliation returns. You may use the Maryland Tax Connect Portal to file Sales & Use Tax and Employer withholding returns. The service applies to filing periods in the current year and back two years. Do not send a paper return if you file using bfile.

To file electronically you need to have:

  • a valid federal employer identification number (FEIN) or Social Security number, AND
  • a Maryland Central Registration Number (your eight-digit Maryland tax account number).

If you have not registered to file Maryland business taxes or do not have a Maryland Central Registration Number, you may register by completing the Maryland Combined Registration Online Application. You will receive the necessary information to file Maryland business taxes approximately one week after submitting your application online.

For bfile system requirements, see bFile Online Service Center General Help

Year End Reconciliation Filing

Employers now have two options to file Form MW508 and W-2 information electronically.

  • W-2 Bulk Upload Application - This application will allow employers and payroll providers to upload income tax withholding statements and W-2s electronically without limitation. More information on the required format of the text file. 1099's cannot be uploaded via this method.


  • The File Withholding Reconciliation (MW508 and W-2 form) application allows employer to data enter up to 250 W-2s and complete the MW508.

File Electronically Through a Tax Preparer

You can also file the following business returns electronically through approved Maryland Online Business Tax Providers.

The list of participating tax preparers does not imply an endorsem*nt of any particular preparer.

Find the Correct Forms

File and submit your payments using the correct tax forms.

Follow the Mailing Instructions and please make sure you complete the name and address area on your form.

Filing Your Taxes in Person

You may submit your paper tax forms and payments, or get assistance in person at any of our local branch offices. Assistance is available 8:30 a.m. - 4:30 p.m., Monday through Friday.

If there is no balance due, businesses may file employer withholding or sales and use tax reports by telephone. Have the tax report with you when you call 410-260-7225. This line is available 24 hours a day, seven days a week.

Business Income Tax Filing Information" (2024)
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