The U.S. tax year runs from January 1 through December 31

The federal tax year is a calendar year. It begins on January 1 and ends on December 31. This is the period for which you report income, claim deductions, and calculate what you owe or what refund you may receive. The IRS uses this same calendar to track all individual and most business tax filings.

Your tax return for a given year is due on April 15 of the following year, unless that date falls on a weekend or federal holiday. For example, your 2024 tax return is due April 15, 2025. The IRS sometimes extends this deadline by a few days if April 15 falls on a Friday or if there is a federal holiday in the District of Columbia.

Key Takeaways

  • The tax year for most people and businesses is January 1 through December 31, matching the calendar year.
  • Tax returns for a given year must be filed by April 15 of the following year, or the next business day if April 15 is a weekend or holiday.
  • Some self-employed people and certain businesses can request a different tax year, called a fiscal year, but this requires IRS permission.
  • Estimated quarterly taxes are due on April 15, June 15, September 15, and January 15 if you are self-employed or have income not subject to withholding.

Who must follow the calendar tax year

Most individual taxpayers, including employees who receive W-2 forms from employers, must use the calendar year. Partnerships, S corporations, and most other business entities also default to the calendar year unless they have received permission from the IRS to use a different one.

If you are an employee and your employer withholds taxes from your paycheck, you report that income on your tax return for the calendar year in which you earned it. Wages paid in December 2024 are reported on your 2024 return, even if you receive the check in January 2025.

Fiscal years and when they apply

A fiscal year is any 12-month period other than the calendar year. Some businesses operate on a fiscal year that ends on a date other than December 31 — for example, June 30 or September 30. Fiscal years are common in retail (which may end after the holiday season) and in agriculture (which may end after harvest).

To use a fiscal year, a business must request permission from the IRS. The IRS does not grant this permission to most sole proprietors or individuals. If you are self-employed as a sole proprietor, you must use the calendar year unless you have a specific business reason and have received written approval from the IRS.

Partnerships and S corporations can use a fiscal year only if all partners or shareholders agree and the IRS approves the request. C corporations have more flexibility and can use a fiscal year without special permission, but they must notify the IRS when they file their first return.

Quarterly estimated tax payments for self-employed people

If you are self-employed or have income that is not subject to withholding — such as rental income, investment income, or freelance work — you may need to make estimated quarterly tax payments. These payments are made four times per year and are based on the income you expect to earn during the calendar year.

Quarterly estimated taxes are due on April 15, June 15, September 15, and January 15. The January 15 payment covers the fourth quarter of the previous calendar year and the first quarter of the current year. If any of these dates falls on a weekend or holiday, the deadline moves to the next business day.

You calculate estimated taxes using Form 1040-ES, which the IRS provides. If you underpay your estimated taxes, you may owe a penalty when you file your annual return, even if you are due a refund overall.

How income is reported based on when you earn it

Income is reported in the tax year in which you earn it, not when you receive payment. If you invoice a client in November 2024 but do not receive payment until February 2025, the income is reported on your 2024 return if you use the cash method of accounting. If you use the accrual method, you report it in 2024 when the invoice is issued, regardless of when payment arrives.

Employees report wages in the year they are earned, based on the pay period. If you receive a paycheck dated December 31, 2024, that income goes on your 2024 return. If the check is dated January 2, 2025, it goes on your 2025 return, even if you receive it in late December 2024.

Bonuses, commissions, and other compensation follow the same rule: report them in the year you earn them, not the year you receive them. Your W-2 form will show the income in the correct year.

Extensions and what they do and do not cover

If you cannot file your return by April 15, you can request an automatic extension from the IRS. Filing Form 4868 gives you until October 15 to submit your return. This extension applies to the filing deadline only, not to the payment deadline.

If you owe taxes, that payment is still due on April 15, even if you have an extension. If you do not pay by April 15, you will owe interest and penalties on the unpaid amount. An extension to file does not extend the time to pay.

If you expect a refund, there is no penalty for filing late. However, the IRS will not process your refund until your return is received and processed. Filing early ensures you receive your refund sooner.

State tax years and how they differ

Most states that have an income tax use the same calendar year as the federal government: January 1 through December 31. Your state return is due on the same day as your federal return, April 15, or a few days later depending on the state.

A few states have different deadlines. Some states allow you to file your state return a few days after the federal deadline. Check your state's tax agency website for the exact date. If you live in a state with no income tax, you do not file a state income tax return, though you may still owe federal taxes.

Frequently Asked Questions

Can I file my tax return before January 1?

No. The IRS does not accept returns for a given year until late January, usually around January 28 or 29. This delay allows employers and financial institutions time to send you the forms you need, such as W-2s and 1099s. Filing before the IRS is ready to receive returns will result in your return being rejected.

What happens if I miss the April 15 deadline?

If you owe taxes and miss the deadline, you will owe a failure-to-file penalty and interest on the unpaid amount. The penalty is usually 5 percent of the unpaid tax for each month the return is late. If you are due a refund, there is no penalty, but you will not receive your refund until the IRS processes your return.

Do I report income I earned in 2024 on my 2024 return or my 2025 return?

Income you earned in 2024 goes on your 2024 return, which you file in 2025. The year of the return is the year you earned the income, not the year you file. Your W-2 or 1099 form will show the correct year.

If I am self-employed, do I have to use the calendar year?

Yes, unless you have received written permission from the IRS to use a fiscal year. Most sole proprietors must use the calendar year. You can request a fiscal year if you have a specific business reason, but the IRS rarely grants this permission to individuals.

Are quarterly estimated tax payments part of the same tax year?

Quarterly estimated taxes are paid during the calendar year and are based on income you expect to earn that year. The payments are made in April, June, September, and January. When you file your annual return, you report the total income you actually earned and the IRS credits the estimated payments you made.