Follow the steps to fill out the IRS 1040 - Schedule 1 online.

1. Press the ‘Get Form’ button to obtain the IRS 1040 - Schedule 1 and open it in your document editor.
2. Fill in your social security number and the names shown on Form 1040 or 1040-SR.
3. Proceed to Part I of the form, where you will report additional income. This includes taxable refunds, alimony received, business income, rental income, unemployment compensation, and any other income you need to report.
4. For each type of additional income, refer to the lines specified. Attach relevant schedules as needed, such as Schedule C for business income or Schedule E for rental income.
5. At the bottom of Part I, combine the amounts from lines 1 through 8 and enter this total on Form 1040 or 1040-SR, line 7a.
6. Move on to Part II for adjustments to income. This section includes educator expenses, health savings account deductions, IRA deductions, and other adjustments.
7. Ensure you attach any required forms or documentation, such as Form 2106 for certain business expenses or Form 8889 for health savings accounts.
8. Sum the amounts listed on lines 10 through 21 to calculate your total adjustments to income and enter this figure on Form 1040 or 1040-SR, line 8a.
9. Once you have completed the form, save your changes, and you can choose to download, print, or share the form as needed.

Complete your IRS 1040 - Schedule 1 online to ensure your tax return is accurate and timely.