top of page
Search

What is Due by September 15 for S‑Corp or Partnership?

aventataxllc
Sep 1
3 min read

September 15 is a major compliance date for Partnerships and S-corporations. It’s when most extended business returns and owner K‑1s must be filed and delivered. Missing it can trigger penalties and delay owner tax planning. Here’s the plain‑English checklist Maryland business owners should consider.




1) Federal filings due September 15 (if you filed an extension)


  • S‑corps file Form 1120‑S and partnerships file Form 1065 by September 15 for calendar‑year entities that extended from the March deadline. Failure to file or filing late can result in substantial penalties.

  • If you have international items, there may be additional forms and requirements. Review these carefully with a tax professional who understands international tax compliance.


2) Maryland specifics to keep on your radar


  • Maryland’s pass‑through entity (PTE) return is Form 510. Its filing date isn’t the same as the federal date; Maryland uses its own due dates. Don’t assume September 15 applies—check your Maryland extension status so your state filing stays on track.

  • What may be due September 15 in Maryland: Q3 estimated PTE payments if you’ve elected the Maryland entity‑level tax or if you owe nonresident member withholding. Make sure to work with a Maryland tax accountant who can advise you on proper filing deadlines, PTET, and other Maryland-specific tax considerations.

  • Sales and use tax and payroll filings run on separate schedules. Keep those calendars separate from your 1120‑S/1065 deadline, but still top of mind.


3) What you should have ready now


  • Clean, reconciled books, including bank accounts and other balance sheet accounts such as Accounts Receivable. This is foundational to accurate tax reporting and proper Maryland small business tax preparation.

  • Officer payroll for S‑corps. Reasonable compensation must be documented before you finalize your 1120‑S.

  • Ownership details. Confirm member/shareholder percentages, basis info, and any Maryland apportionment/allocation if you operate in multiple states.



4) When to call a professional instead of DIY


  • You operate in more than one state, have foreign activity, or received an IRS/state notice.

  • Your business considered or made a Maryland PTE election and needs help computing Q3 estimates due September 15.

  • You’re late getting K‑1s to owners or anticipate amended returns.

  • You want proactive planning around S‑corp payroll, partner guaranteed payments, or Maryland credits. This is where a small business accountant in Montgomery County, MD is valuable -- a tax advisor who understands the local market and guidelines to ensure compensation is aligned.


How Aventa Tax helps before September 15

  • Business tax preparation and planning for S‑corporations and partnerships. Our Maryland tax advisors can help you prepare and file 1120-S and 1065, accurately and timely. We provide business tax services in Germantown, Rockville, Bethesda, Silver Spring, and surrounding areas.

  • Bookkeeping and financial reporting support with QuickBooks or Xero to get your financials filing‑ready quickly—part of our accounting services in Montgomery County, MD.

  • Maryland PTE strategy and estimates. Our team of tax professionals can help you plan around PTE and other Maryland-specific tax components.



Aventa Tax is a local Maryland firm supporting service‑based businesses, contractors, law practices, consultants, and medical practices. If you need a tax accountant in Montgomery County, MD who knows S‑corps, partnerships, and Maryland PTE rules, our team can help. We provide Maryland small business tax preparation that’s timely, thorough, and practical. September 15 shouldn't become a fire drill. When you want a calm, experienced tax preparer in Montgomery County, MD in your corner, call us.



Aventa Tax can organize your books and file tax returns correctly. To discuss your situation and get small business tax services in Montgomery County Maryland, call our office at 301-235-2724 or learn more about business tax planning and business taxes for LLCs.


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

 
 
 

Comments

bottom of page