small business tax deadline calendar

the deadlines that carry penalties

Quarterly estimated tax (Apr 15, Jun 15, Sep 15, Jan 15) carries the underpayment penalty calculated per quarter. Quarterly payroll Form 941 (Apr 30, Jul 31, Oct 31, Jan 31) and the annual Form 940 (Jan 31) carry late-filing and late-deposit penalties. W-2 and 1099 delivery to recipients and filing with agencies are both due January 31.

S-corp and partnership returns are due March 15 (extended to September 15). C-corp and individual returns are due April 15 (extended to October 15). Each carries a late-filing penalty that scales with how late and, for pass-throughs, per-owner.

• Quarterly estimates: Apr 15 · Jun 15 · Sep 15 · Jan 15
• Form 941 (payroll quarterly): Apr 30 · Jul 31 · Oct 31 · Jan 31
• Form 940 (FUTA annual) + W-2/1099 filing: Jan 31
• S-corp/partnership returns: Mar 15 (extended Sep 15)
• C-corp/individual returns: Apr 15 (extended Oct 15)

weekend and holiday shifts

When a deadline falls on a weekend or holiday, it shifts to the next business day. This sounds trivial but it shifts the planning — a January 31 that lands on a Saturday becomes February 2, and a business that planned for the 31st has to file by the Monday or pay the penalty.

AA tracks every federal and state date that applies to a client's business and sends reminders before each one, so a shifted deadline never becomes a surprise penalty.

extensions to file are not extensions to pay

An extension gives you more time to file the return — not more time to pay the tax. Unpaid balances accrue interest and the failure-to-pay penalty from the original due date. An extension is a filing tool, not a payment plan.

The right use of an extension is to buy time to gather documents or finalize a complex return while an estimated payment covers the liability by the original deadline.

state deadlines differ

State deadlines often differ from federal, especially for pass-through entity taxes, sales tax, and franchise taxes. Missing a state deadline is the most common 'surprise' penalty for businesses that only track the federal calendar. Some states align their due dates with federal; many don't.

Sales tax filings in particular can be monthly, quarterly, or annually depending on volume, and missing them carries both a penalty and, in some states, personal liability for the owner. AA maintains the full federal and state deadline calendar for each client.