The federal IRS filing and payment deadlines US accounting and CPA firms work to in 2027, for calendar-year 2026 returns and 2027 estimated tax. Dates that fall on a weekend or legal holiday are already moved to the next business day.
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If a due date falls on a Saturday, Sunday, or legal holiday, a return or payment is on time if made by the next day that is not a Saturday, Sunday, or legal holiday. Legal holidays are those of the District of Columbia; statewide holidays can also delay a filing date for that state. This calendar covers general rules for most filers; a client’s own facts can change a deadline. It is guidance, not tax advice.
| Due | Deadline |
|---|---|
| Fourth-quarter 2026 estimated tax payment Individuals who pay estimated tax (Form 1040-ES) Due the 15th day of the first month after the tax year ends. |
| Due | Deadline |
|---|---|
| Forms W-2 to employees and to the SSA Employers Due January 31. January 31, 2027 is a Sunday, so the deadline moves to Monday, February 1. | |
| Form 1099-NEC to recipients and the IRS Businesses that paid nonemployee compensation Due January 31, moved to February 1 because January 31, 2027 is a Sunday. |
| Due | Deadline |
|---|---|
| Form 1065 and Schedule K-1s Calendar-year partnerships Due the 15th day of the third month after year-end. Form 7004 extends the time to file by six months. | |
| Form 1120-S and Schedule K-1s Calendar-year S corporations Due the 15th day of the third month after year-end. Form 7004 extends the time to file by six months. |
| Due | Deadline |
|---|---|
| Form 1040 filing and payment, or Form 4868 extension Individuals Due the 15th day of the fourth month after year-end. Form 4868 extends the time to file to October 15, not the time to pay. | |
| Form 1120, or Form 7004 extension Calendar-year C corporations Due the 15th day of the fourth month after year-end, with an automatic six-month extension on Form 7004. | |
| First-quarter 2027 estimated tax payment Individuals who pay estimated tax Due the 15th day of the fourth month of the tax year. |
| Due | Deadline |
|---|---|
| Second-quarter 2027 estimated tax payment Individuals who pay estimated tax Due the 15th day of the sixth month of the tax year. |
| Due | Deadline |
|---|---|
| Extended Forms 1065 and 1120-S Calendar-year partnerships and S corporations that filed Form 7004 Six months after the original March 15 deadline. | |
| Third-quarter 2027 estimated tax payment Individuals who pay estimated tax Due the 15th day of the ninth month of the tax year. |
| Due | Deadline |
|---|---|
| Extended Form 1040 Individuals who filed Form 4868 Six months after the original April 15 deadline. | |
| Extended Form 1120 Calendar-year C corporations that filed Form 7004 Six months after the original April 15 deadline. |
A calendar tells you when something is due. It does not tell you which clients it applies to, who owns each filing, or what is still waiting on the client. In CPA Buddy, each filing is an engagement with a due date and an owner, and your team gets automatic due-date reminders before it slips. A pre-loaded tax calendar is coming soon.
