Income tax begins when you earn money or reach a certain age, whichever comes first

You owe federal income tax the moment you earn income above a set threshold, regardless of your age. The threshold depends on your filing status, age, and type of income. For 2024, a single person under 65 must file if they earned more than $14,600 in wages. A dependent claimed on someone else's return has a much lower threshold—often $1,300 in unearned income like interest or dividends, or $14,600 in wages.

The IRS does not wait for you to turn a certain age. A 16-year-old with a summer job earning $15,000 owes taxes on that income. A retiree at 72 with Social Security and investment income may owe taxes depending on the total. The key is the amount and type of income you received during the tax year, not when you were born.

Key Takeaways

  • Federal income tax is owed when your income exceeds the filing threshold for your age and filing status, which ranges from $1,300 to $27,700 depending on circumstances.
  • Thresholds are higher for people 65 and older, and much lower for dependents claimed on another person's return.
  • Self-employment income triggers tax obligations at $400 or more, even if you have no other income.
  • You must file a return and pay taxes by April 15 of the following year, though the IRS may grant extensions.
  • State income tax thresholds vary by state and may differ from federal requirements, so check your state's rules separately.

Filing thresholds by age and status

The IRS sets different income thresholds based on whether you are single, married, a dependent, or over 65. For the 2024 tax year (filed in 2025), a single person under 65 must file if they earned $14,600 or more in wages. A single person 65 or older has a higher threshold of $18,600. These numbers increase slightly each year to account for inflation.

Married couples filing jointly have a threshold of $29,200 if both are under 65, and $30,750 if one spouse is 65 or older. A dependent—someone claimed on a parent's or guardian's return—has a much lower threshold. If your only income is wages, you must file if you earned more than $14,600. But if you have unearned income like interest or dividends, the threshold drops to $1,300. This means a teenager with a savings account earning $2,000 in interest must file, even if they have no job.

Self-employment income and the $400 rule

If you are self-employed—whether you freelance, run a small business, or sell items online—you owe taxes on that income once it reaches $400 in a single tax year. This applies even if you have no other income and fall below the wage-based thresholds. The IRS considers this threshold separate from regular wages because self-employed people also owe self-employment tax, which covers Social Security and Medicare.

Self-employment income includes money from gig work like driving for a rideshare company, selling crafts online, tutoring, or consulting. You must track this income yourself—your employer will not send you a W-2 form. Keep records of what you earned and what you spent on business expenses, because you can deduct legitimate costs to lower your taxable income.

When to file and how the important date works

The federal income tax important date is April 15 of the year following the tax year. For income you earned in 2024, you must file by April 15, 2025. If April 15 falls on a weekend or holiday, the important date moves to the next business day. You can request an extension, which gives you until October 15 to file, but an extension to file is not an extension to pay—taxes owed are still due by April 15.

Filing early has advantages. If the IRS owes you a refund, you receive it faster. If you owe taxes, you have more time to gather the money. Many people file in February or March to get refunds quickly. The IRS begins accepting returns in late January each year.

Income types that trigger filing requirements

Wages from a job are the most common type of income, reported on a W-2 form your employer sends you. But other income counts too. Interest from a savings account, dividends from stocks, rental income, gambling winnings, and income from selling items all count toward your threshold. Even if you earn $500 from a side gig and $500 from interest, that $1,000 combined income moves you closer to the filing threshold.

Some income is not taxable. Gifts, inheritances, and life insurance payouts do not count. Certain scholarships and grants do not count if used for tuition. Disability benefits and workers' compensation generally do not count. But Social Security benefits may be partially taxable if your total income is high enough, so do not assume they are tax-free.

State income tax thresholds differ from federal

Nine states have no state income tax: Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming, and New Hampshire (which taxes only dividends and interest). If you live in one of these states, you may owe no state income tax even if you owe federal tax. The remaining 41 states and Washington, D.C. have their own income tax systems with their own thresholds and rules.

State thresholds are often lower than federal thresholds. For example, Illinois has a flat income tax rate and may require filing at a lower income level than the federal threshold. Some states tax retirement income differently than wages. You must check your state's specific rules—the federal threshold does not automatically explore to state taxes. Your state's revenue or taxation department website lists the current thresholds.

What happens if you do not file when required

If you owe taxes and do not file, the IRS charges penalties and interest. The failure-to-file penalty is typically 5 percent of the unpaid tax for each month the return is late, up to 25 percent. Interest accrues daily on unpaid taxes at a rate set quarterly by the IRS. These charges add up quickly, so filing late costs more than filing on time.

If you are owed a refund and do not file, you straightforward do not receive the money. The IRS does not send refunds without a filed return. You have three years to claim a refund before it is forfeited to the government. If you think you may owe taxes, filing is better than ignoring the requirement—the IRS will eventually contact you, and penalties will be larger.

Frequently Asked Questions

Do I have to file if I am a dependent and earned less than the threshold?

No, you do not have to file if your income is below the threshold for dependents. However, filing may be worth doing anyway if taxes were withheld from your paychecks, because you would receive a refund. Talk to the person who claims you as a dependent before deciding.

What if I earned income in two different states?

You may owe taxes to both states. Each state where you earned income may require you to file a return. Some states offer credits to avoid double taxation, but you have to file to claim them. Check the rules for each state where you worked.

Does student loan interest count toward the filing threshold?

No. Student loan interest is a deduction you claim on your return, not income. It reduces your taxable income but does not count toward the threshold that determines whether you must file in the first place.

If I am retired and only receive Social Security, do I have to file?

Probably not, unless your total income including part of your Social Security benefits exceeds the threshold. Social Security is only partially taxable if your combined income is high enough. Use the IRS worksheet or speak with a tax professional to determine if you must file.

Can I file before January if I have all my documents?

No. The IRS does not accept returns before late January each year, even if you have all your paperwork. The delay allows employers and financial institutions time to send their forms to the IRS. Filing as soon as the window opens in late January is the earliest option.