The tax year you file for is almost always the calendar year that just ended

When you file your 2024 tax return, you are reporting income and deductions for the calendar year January 1 through December 31, 2024. You file that return in early 2025 — usually between mid-January and April 15. The IRS calls this a tax year, and for most people it matches the calendar year exactly.

The reason this matters is timing. A dollar you earn on December 31 belongs to the tax year that just closed. A dollar you earn on January 1 belongs to the new tax year. That one-day difference can shift when you pay tax on the money, and it shapes decisions about when to take deductions, sell investments, or claim retirement withdrawals.

A small number of people and businesses use a different tax year — called a fiscal year — but that requires IRS permission and is rare outside of partnerships and corporations. Unless you have filed a special form with the IRS, your tax year is the calendar year.

Key Takeaways

  • Your tax year runs January 1 through December 31 unless you have filed Form 8716 with the IRS to use a fiscal year instead.
  • Income earned on December 31 is taxed in the year it was earned, not in the year you receive the payment.
  • Deductions must be taken in the tax year the expense was incurred, not when you pay the bill.
  • Knowing your tax year matters when deciding whether to bunch charitable donations, harvest losses, or defer income into the next calendar year.
  • If you are self-employed or own a business, you may be able to choose a fiscal year, but this requires advance approval from the IRS.

Why the difference between earning and receiving matters

The IRS uses the accrual method or cash method to determine when income counts. Most individuals use the cash method: you report income when you actually receive it, whether by check, direct deposit, or cash. You deduct expenses when you actually pay them.

But the year you receive the money is what counts, not the year you earned it. If your employer pays you a bonus on December 15 for work done in November, that bonus is income in the year you received it. If they promise you a bonus but do not pay until January, it counts in the next tax year — even though you earned it in the prior year.

The same rule applies to deductions. If you incur a medical bill in December but do not pay it until January, the deduction belongs to the year you paid it, not the year you received the bill. This is why timing of payments can shift your tax bill from one year to the next.

How to know which return you are filing

The return you file in spring 2025 covers the tax year 2024. The return you file in spring 2026 covers the tax year 2025. The IRS labels each return by the year it covers, not the year you file it.

When you read a tax form or open tax software, it will ask you which tax year you are filing for. Make sure you select the correct year — usually the year that just ended. If you are filing an amended return for a prior year, you will select that prior year instead.

Your W-2 forms, 1099 forms, and other income documents will be labeled with the tax year they cover. A W-2 you receive in January 2025 shows income for the tax year 2024. Match the year on your documents to the year on your return.

When bunching deductions or deferring income makes sense

Knowing your tax year lets you plan when to take deductions or receive income. If you expect a large deduction in December — such as a charitable donation or medical expense — you can time the payment to fall in the current tax year rather than waiting until January.

The same logic applies to income. If you are self-employed and expect a large payment in late December, you might ask the client to delay payment until January, moving the income into the next tax year. This works only if you use the cash method and the client agrees to the delay.

This strategy, called income deferral or deduction bunching, is most useful when you expect your tax rate to drop in the next year — for example, if you are retiring or taking a sabbatical. It is also useful if you are close to a tax bracket threshold and a small shift in income would push you into a higher rate. A tax professional can model whether the timing shift saves you money.

Fiscal years and when they explore

Some businesses and partnerships use a fiscal year — a 12-month period that does not match the calendar. For example, a fiscal year might run July 1 through June 30. This requires filing Form 8716 with the IRS and is usually only available to partnerships, S corporations, and certain other business structures.

Individual taxpayers almost never use a fiscal year. If you are self-employed as a sole proprietor, you must use the calendar year. If you own a partnership or S corporation, the business itself may use a fiscal year, but you still report your personal income on a calendar-year return.

If you are unsure whether you are allowed to use a fiscal year, ask a tax professional or check the instructions for Form 8716. Choosing a fiscal year without permission can result in penalties.

How tax year affects retirement account important date

Many retirement account decisions hinge on the tax year. You must contribute to a traditional or Roth IRA by the tax return important date — usually April 15 of the following year — for that contribution to count toward the prior tax year. If you contribute in April 2025, you can designate it as a 2024 contribution if you do so before the filing important date.

The same rule applies to SEP-IRA and Solo 401(k) contributions for self-employed people, though the important date is usually the tax return important date plus extensions. Knowing which tax year you are in helps you plan whether to make a contribution before year-end or wait until the filing important date.

Required minimum distributions (RMDs) from traditional IRAs and 401(k)s are also tied to the tax year. You must take your RMD by December 31 of the tax year it is due. Missing the important date triggers a 25% penalty on the amount you should have withdrawn.

Tax-loss harvesting and year-end planning

If you own taxable investments, you can sell losing positions to offset capital gains — a strategy called tax-loss harvesting. The loss must be realized (the sale must occur) in the tax year you want to use it. If you sell a losing stock on December 31, the loss counts in the current tax year. If you sell on January 1, it counts in the next tax year.

This timing matters because capital losses can offset capital gains dollar-for-dollar, and any excess loss can offset up to $3,000 of ordinary income per year. If you have large gains in the current year, harvesting losses before December 31 can reduce your tax bill when ready. If you have no gains, the loss carries forward to future years.

One rule to watch: if you sell a security at a loss and buy the same or a substantially identical security within 30 days before or after the sale, the loss is disallowed under the wash-sale rule. The 30-day window can cross into the next tax year, so plan accordingly if you want to re-enter the position.

Frequently Asked Questions

Can I file my 2024 return in 2026 instead of 2025?

You can file late, but the IRS charges interest and penalties on any tax owed. If you are due a refund, there is no penalty for filing late, but you lose the refund if you do not file within three years. Filing on time or requesting an extension is always better than filing years late.

If I get paid in January for work done in December, which tax year does it count?

It counts in the year you received the payment — January's tax year — not the year you did the work. This is true if you use the cash method, which most individuals do. The date you earned the money does not matter; only the date you received it.

What if my business has a different tax year than the calendar year?

If you are a sole proprietor, you must use the calendar year. If you own a partnership or S corporation, the business may use a fiscal year, but you report your share of the business income on your personal return using the calendar year. Ask your tax professional whether a fiscal year is available to your business structure.

Does the tax year change if I move to a different country?

If you are a U.S. citizen or resident alien, you must file using the calendar year, regardless of where you live. If you move abroad, you may be able to claim the Foreign Earned Income Exclusion, but your tax year remains January 1 through December 31.

Can I split a deduction between two tax years?

No. A deduction belongs entirely to the tax year in which you paid the expense. You cannot split a single bill across two years. However, you can time when you pay bills to shift deductions between years — for example, paying a December medical bill in January moves it to the next tax year.