Side-income tax calendar, November 2026 to October 2027

Updated November 2026 · 2026 tax year · 7 minute read

Missing a tax deadline is expensive, and it is easy to do when your side income does not come with a paycheck reminder. This calendar lists the dates that matter for people with side income over the next year: when estimated payments are due, when 1099 forms arrive, when to file, and what to do at year end. All dates are federal. Your state may have its own.

How the dates are set

Federal deadlines that fall on a Saturday, Sunday or legal holiday move to the next business day. Estimated tax payments are due on April 15, June 15, September 15 and January 15, and the dates below already reflect weekends and holidays. For a deeper explanation of who has to pay and how much, see our guide to quarterly estimated taxes.

Key dates at a glance

November and December 2026: plan before the year ends

• Check your profit year to date. Compare it with your estimate. If your side income has grown, your Q4 payment should grow too. Our calculator can quickly rerun the numbers.
• Time your purchases. If you were already planning to buy business equipment or supplies, buying before December 31 means the deduction counts for 2026. Do not buy something you do not need just for the deduction, since you still spend the money.
• Review retirement options. A solo 401(k) is easier if it is established early. See retirement accounts for the self-employed.
• Update your mileage log and note the year-end odometer reading on December 31 or 1. See the mileage guide.
• Collect W-9 forms from any contractor you paid, if you hire people for your side business.
• Consider a W-4 change. If you realize late in the year that you will owe more, extra withholding at your day job can cover the shortfall and is treated as if paid evenly through the year.

January 2027

The fourth-quarter estimated payment for 2026 is due on January 15. There is a way to skip it: if you file your 2026 return and pay the full balance by the end of January (or the next business day), you do not need to make the January 15 payment. Few side-income earners will have everything ready that early, but it is worth knowing about.

The deadline for businesses and platforms to send you a 1099-NEC is February 1, 2027. Forms from payment platforms usually arrive in late January. Download them as they appear and compare them with your own records. Our 1099 guide explains each form.

February and March 2027

This is the right time to pull your records together, work out your profit for the year, and choose whether to file yourself or hire a preparer. Gather your Schedule C information: income by source, expenses by category, mileage, home office measurements, and your estimated payments made during the year. If you sent 1099s to anyone, make sure they were filed on time. The recordkeeping guide shows how to get ready.

April 15, 2027: the big date

Several things are due on April 15:

• Your 2026 federal tax return, or an extension request.
• Any balance you owe for 2026. An extension gives you more time to file but not more time to pay, so estimate your balance and pay it by April 15 to avoid penalties and interest.
• Your first-quarter 2027 estimated payment.
• Contributions to a traditional or Roth IRA for 2026.
• Your state return and any state payments, in most states.

June, September and October 2027

The second-quarter payment is due on June 15, and the third-quarter payment on September 15. Remember that the periods are uneven: the second payment covers just two months. If you filed an extension, your return is due on October 15, 2027. That is also the deadline for funding a SEP-IRA for 2026 if you extended. Treat the payment dates as your quarterly reminders, and use a mid-year check to reset your estimates.

State dates

Most states with an income tax follow a similar schedule, but not all. California, for example, uses payment weights of 30%, 40%, 0% and 30% for its installments rather than splitting them evenly, and some states have different filing dates. Check your state's revenue department, and read our state tax guide.

Penalties and what to do if you miss a date

If you miss a payment, pay as soon as you can. The penalty for underpayment is calculated by period and grows with the time a shortfall stays unpaid. If you miss the April filing deadline without an extension, there is a separate failure-to-file penalty that is generally larger than the failure-to-pay penalty, so filing on time, or extending, matters even if you cannot pay everything. The IRS has payment plans for taxpayers who cannot pay in full.

A simple way to stay on schedule

Put the four estimated payment dates and the April filing date in your calendar now, with a reminder one week ahead. Transfer your set-aside money every time you are paid, and use the calendar dates as the moment to review your profit and adjust the next payment. If you do that, nothing on this list will catch you off guard.

Run the numbers with the free calculator

This guide is general information, not tax advice. Tax rules change and individual circumstances differ. Confirm the details for your situation with the IRS or a licensed tax professional.