Q3 Estimated Taxes: Do I Need to Pay by September 15, and How Do I Calculate and Submit It?

The year moves fast, and the September 15th deadline can sneak up on business owners, particularly when it comes to estimated tax payments. For Maryland businesses, staying on top of Q3 helps you avoid federal and state underpayment penalties and keeps year-end filing smooth.

Here are a few key points for success:

1) Who must pay by September 15 (for individuals or pass-through-entities)

• Individuals (including Schedule C filers)

• S corporations and partnerships: The entity usually doesn’t owe federal income tax, but you may owe Maryland pass-through entity (PTE) estimated tax if you’ve elected the Maryland PTE tax or owe nonresident member tax. If you did not elect PTE tax, owners typically handle tax at the owner level, but entity cash flow planning still matters.

• LLCs: Taxed as C corp, S corp, or partnership depending on your election. Your estimated tax obligations follow the election.

  
  

2) Different methods to estimate

• Safe-harbor shortcut: Use last year’s total tax as a baseline (110% of prior year tax liability is a very conservative approach). Pay one quarter of that amount (adjust for what you’ve already paid in Q1 and Q2). This can reduce penalty risk when income is steady, but you risk overpaying.

• Year-to-date method: Project full-year profit based on bookkeeping through August, then apply your applicable federal and Maryland business tax rates. Subtract estimates already paid to get your Q3 amount.

• PTE election: If you elected the Maryland PTE tax, estimate based on expected Maryland-source taxable income for the entity and the applicable PTE rates. Prior-year PTE tax is a useful benchmark when income is similar.

Estimated tax planning and projections require solid financials, as these are what the projections are based on. It is essential that you have clean, accurate books in place for making reasonable tax estimates. For example, our team provides accounting services for businesses in Gaithersburg, Silver Spring, Bethesda, Rockville and nearby areas using cloud tools like QuickBooks and Xero to help keep numbers current so estimates are accurate.

3) How to submit the Q3 payment

• Federal - the best way to make estimated tax payments is via an IRS online account. You can find full guidance on payment methods here Payments | Internal Revenue Service.

• Maryland - pay electronically through the Comptroller’s payment options. See MD guidance Tax Guidance - Payment Methods - Taxpayer Services.

• Keep it consistent: Match EINs, tax periods, and “Q3” selections to avoid misapplied payments.

4) When to call a professional

• Profit swings, seasonal spikes, or multi-state income.

• Considering or already using the Maryland PTE tax election.

• Entity changes (LLC to S corporation) mid-year.

• You claim credits (e.g., payroll-related or Maryland business credits) that affect estimates.

As a small business accountant in Germantown Maryland, Aventa Tax can review your year-to-date books, firm up a Q3 number, and assist you with scheduling payments so you avoid penalties. Our team provides expert accounting services that incorporate help with estimated taxes for business owners.

If you’re unsure about your Q3 estimate or the Maryland PTE rules, Aventa Tax delivers comprehensive business tax services in Montgomery County, Maryland and surrounding areas to keep you compliant. For personalized estimated tax guidance from a Maryland tax accountant, call our office at 301-235-2724 or learn more about quarterly estimated tax help or business tax services.

Disclaimer: This information is for educational purposes only. Please consult a tax professional for specific advice on your situation.