Tax Deadlines for Q2 2026: Federal and Maryland Guide

Spring is here, and so is one of the busiest stretches of the tax calendar. The second quarter of the year — April through June — is packed with critical federal and Maryland state deadlines that can catch even the most organized business owners off guard. Miss one, and you could be looking at penalties, interest, or complications with your business standing.

At Insightful Accounting Services, we work with businesses right here in Columbia and across Howard County to help them stay ahead of these dates. Here's your complete Q2 deadline guide for 2025.

April 15 — The Big Tax Deadline

Most people associate April 15 with personal income taxes, and that's true — but for business owners, this date carries a lot more weight.

Federal Corporate Income Tax Returns Due (Form 1120) Calendar-year C-corporations must file their federal corporate income tax return (Form 1120) by April 15. If your corporation needs more time, you can file Form 7004 to request an automatic six-month extension, pushing your filing deadline to October 15 — but as with all extensions, any tax owed is still due on April 15 to avoid penalties and interest. Maryland corporate income tax returns (Form 500) follow the same April 15 deadline for calendar-year filers, with a corresponding extension available.

Note: S-corporations and partnerships had their returns due on March 15. If you missed that deadline, contact us right away.

Federal Individual Income Tax Returns Due If you're a sole proprietor, partner, or S-corp shareholder, your personal return (Form 1040) is due today. This is also the deadline to file for an extension (Form 4868), which gives you until October 15 to file — but remember, an extension to file is not an extension to pay. Any taxes owed are still due today to avoid penalties and interest.

Maryland Annual Report — Due to the State Department of Assessments and Taxation (SDAT) All Maryland corporations, LLCs, limited partnerships, and other registered business entities must file their Annual Report and Personal Property Return with the Maryland SDAT by April 15. This is not optional — failure to file can result in your business being forfeited (losing its good standing) with the state. The filing fee varies by entity type.

Maryland Withholding Tax — Monthly Filers If your business withholds Maryland income tax from employee wages and you are a monthly filer, your withholding deposit for March is due on April 15. This is filed using Maryland Form MW506.

Federal Estimated Tax Payments — Q1 If you are self-employed or have income not subject to withholding, your first estimated tax payment for 2025 (covering January–March) is also due on April 15. Use IRS Form 1040-ES to calculate and submit your payment.

April 20 — Maryland Sales & Use Tax

Maryland Sales and Use Tax Return Due Maryland sales tax returns are due on the 20th of the month following the reporting period. For most businesses, the March sales and use tax return is due on April 20. Retailers and businesses that collect sales tax in Maryland must file and remit their collections by this date.

If you are a quarterly filer, your Q1 sales tax return (January–March) is also due on April 20. Not sure which filing frequency applies to you? It depends on your average monthly tax liability — contact our office and we can confirm your filing status.

April 30 — Maryland Withholding Tax (Quarterly Filers)

Maryland Employer Withholding — Q1 Quarterly Return If your business files Maryland employer withholding taxes on a quarterly basis, your Q1 return (covering January, February, and March) is due April 30. This is filed on Maryland Form MW506 and must include all wages paid and Maryland income tax withheld during the first quarter.

This is also a good time to reconcile your payroll records to make sure your deposits throughout the quarter match what you're reporting.

June 15 — Mid-Year Checkpoints

Federal Estimated Tax Payments — Q2 Your second estimated tax payment for 2025 (covering April–May) is due on June 15. Don't let the summer sneak up on you — this payment is a common one to miss, especially for business owners juggling a busy season. Underpaying estimated taxes can result in an underpayment penalty when you file your return.

Maryland Annual Report — Extension Deadline If you were unable to file your Maryland Annual Report by April 15, you may have requested an extension. June 15 is the extended deadline for filing your Maryland Annual Report with SDAT. Note that this is a filing extension only — any fees or taxes owed are still calculated from the original April 15 date. Operating past the original deadline without filing can put your business's good standing at risk, so if you took an extension, make sure June 15 is on your calendar.

Maryland Withholding Tax — Monthly Filers Monthly withholding filers: your May withholding deposit is due June 15.

Don't Wait Until the Last Minute

These deadlines come faster than you'd expect, and the penalties for missing them can add unnecessary stress and cost to your operations. We are located right here in Columbia, Maryland, and we specialize in helping small and mid-sized businesses stay compliant, organized, and financially healthy year-round.