Business Tax Calendar: Federal Filing Deadlines & Quarterly Estimates

Missing a filing date is one of the most avoidable and expensive mistakes in business taxation, because penalties accrue automatically and compound. The federal calendar is entity-specific: pass-through returns are due a month before individual returns, information returns have their own January cliff, and the self-employed must prepay through four uneven quarterly installments. The reference below organizes every core deadline and the rules that move them.

Annual Return Deadlines by Entity

The annual return date depends entirely on entity type. Partnerships (Form 1065) and S-corporations (Form 1120-S) file by March 15 for calendar-year taxpayers. Individuals and single-member LLCs reporting on Schedule C, along with calendar-year C-corporations (Form 1120), file by April 15. The earlier pass-through date exists so that owners receive their Schedule K-1s before their own April deadline.

Extensions buy time to file but not time to pay. Form 7004 extends partnership and corporate returns — pushing Form 1065 and Form 1120-S to September 15 and Form 1120 to October 15 — while Form 4868 extends an individual return to October 15. Any tax owed is still due on the original date, and interest runs on unpaid balances from that date forward.

Key Federal Deadline Matrix

The matrix lists each core return, its entity, the original date, and the extended date.

The Quarterly Estimated-Tax Schedule

Because no employer withholds on their behalf, taxpayers who expect to owe $1,000 or more for the year must make quarterly estimated payments using Form 1040-ES. These installments cover both projected income tax and self-employment tax. The four periods are deliberately uneven: April 15 covers January through March, June 15 covers April and May, September 15 covers June through August, and January 15 of the following year covers September through December.

A safe harbor shields compliant taxpayers from underpayment penalties: pay at least 90 percent of the current-year liability or 100 percent of the prior-year tax (110 percent if prior-year adjusted gross income exceeded $150,000). Payments are timestamped through IRS Direct Pay or EFTPS, eliminating disputes over timeliness.

Information-Return Deadlines

Information returns carry a hard January 31 deadline that catches many new businesses. Form 1099-NEC, reporting $600 or more paid to a nonemployee for services, must be furnished to the recipient and filed with the IRS by January 31. Form W-2 must likewise reach employees and the Social Security Administration by January 31. Form 1099-MISC for other payment types and Form 1099-K from payment platforms follow their own schedules.

Late information returns draw tiered, per-form penalties that escalate the longer they remain unfiled, and intentional disregard carries the steepest charge. Because these forms feed the recipients’ own filings, late or incorrect issuance creates downstream compliance problems beyond the issuer’s own penalty.

Extensions, Weekends, and Penalty Mechanics

When any deadline falls on a Saturday, Sunday, or federal holiday, it rolls forward to the next business day. Two distinct penalties apply to late annual returns: the failure-to-file penalty of 5 percent of unpaid tax per month (up to 25 percent) and the milder failure-to-pay penalty of 0.5 percent per month. When both apply in the same month, the failure-to-file penalty is reduced by the failure-to-pay amount.

Interest accrues separately from penalties on any unpaid balance at the federal short-term rate plus three percentage points, adjusted quarterly and compounded daily. The practical takeaway is to file on time even when you cannot pay in full, because the failure-to-file penalty is ten times the failure-to-pay rate.