What form is primarily used to file individual income tax returns in the United States?

The form primarily used to file individual income tax returns in the United States is Form 1040. This form is designed for reporting income, calculating taxes owed, and determining eligibility for various credits and deductions. It serves as the main document for taxpayers to report their earnings, claim exemptions, and mitigate their tax liabilities, making it essential for the individual tax filing process.

Form 1010 is not a standard tax form recognized by the IRS for individual filings. Form 1120 is specifically used for corporate tax returns, pertaining to corporations and their income, while Form W-2 is a wage and tax statement provided by employers to report wages paid to employees and the taxes withheld, but it is not used to file income tax returns by individuals. Therefore, Form 1040 is the correct and most commonly utilized form for individual income tax returns in the U.S.