26 U.S.C. § 6012: Who Is Required to File a Tax Return?
Understand the specific criteria that establish a legal duty to file a U.S. tax return, from gross income thresholds to other mandatory circumstances.
Federal law establishes a legal duty for certain entities and individuals to file an annual income tax return with the Internal Revenue Service (IRS). The specific rules outlining who must file are detailed in the Internal Revenue Code. At the heart of these rules is 26 U.S.C. § 6012, which provides the foundational requirements for filing. This section defines the circumstances under which individuals, corporations, and fiduciaries must report their income based on criteria like gross income and entity type.
Filing Requirements for Individuals
The primary factor determining if an individual must file a tax return is their gross income. Gross income includes all income received in the form of money, goods, property, and services that is not exempt from tax. The dollar amount that triggers the filing requirement depends on filing status, age, and dependency status. For the 2025 tax year, these thresholds are linked to the standard deduction.
A single individual under age 65 must file if their gross income is at least $15,000, which increases to $17,000 for those age 65 or older.
For those who are married and filing a joint return, the threshold is $30,000 if both spouses are under 65. If one spouse is 65 or older, the amount increases to $31,600, and if both spouses are 65 or older, it rises to $33,200.
An individual married filing separately must file a return if their gross income is just $5. Head of household filers have a threshold of $22,500 if under age 65, increasing to $24,500 for those 65 or older. A qualifying surviving spouse must file if their gross income is at least $30,000 if under 65, or $31,600 if 65 or older.
Dependents
The filing rules for individuals who can be claimed as a dependent are distinct and depend on the type of income received. Earned income includes salaries and wages, while unearned income consists of investment-type income like interest and dividends.
For the 2025 tax year, a dependent must file a return if their unearned income was more than $1,350 or their earned income was more than $15,000. If the dependent has both, they must file if their gross income was more than the larger of either $1,350 or their earned income (up to $14,550) plus $450.
Filing Requirements for Corporations
Every domestic corporation subject to taxation under the Internal Revenue Code must file an income tax return, regardless of whether it had taxable income for the year. This obligation is tied to the corporation’s existence, not its profitability, and applies even if the corporation was inactive.
S corporations file Form 1120-S, and their deadline is the 15th day of the third month following the close of their tax year—March 15 for calendar-year corporations. C corporations file Form 1120, and their deadline is the 15th day of the fourth month after their tax year ends, typically April 15. Failure to file on time can result in significant penalties.
Filing Requirements for Fiduciaries
A fiduciary is a person or entity, such as an executor of an estate or a trustee of a trust, that manages assets for a beneficiary. Fiduciaries may need to file Form 1041, U.S. Income Tax Return for Estates and Trusts, for the entity they administer.
A domestic decedent’s estate must file Form 1041 if it has gross income of $600 or more for the tax year. An estate must also file, regardless of income, if any of its beneficiaries are nonresident aliens. The executor is responsible for filing this return.
A domestic trust must file Form 1041 if it has any taxable income for the year, or if it has gross income of $600 or more. Similar to an estate, a trust must also file if it has a nonresident alien as a beneficiary. The trustee is responsible for filing the return, and the deadline for calendar-year estates and trusts is April 15.
Other Mandatory Filing Situations
Beyond the standard gross income thresholds, several other situations can trigger a mandatory filing requirement for an individual, even if their total gross income is relatively low. These situations include:
- Having net earnings from self-employment of $400 or more.
- Owing special taxes, such as the alternative minimum tax, additional taxes on a qualified plan like an IRA, or household employment taxes.
- Receiving distributions from a Health Savings Account (HSA), Archer MSA, or Medicare Advantage MSA.
- Receiving advance payments of the premium tax credit for health insurance purchased through the Health Insurance Marketplace, which requires filing to reconcile the payments.
Even if a person is not required to file, it may be beneficial to do so if they had federal income tax withheld from their pay or if they qualify for refundable tax credits.