The IRS is likely asking for interest earned in your retirement accounts, such as a 401(k). Usually, you don't report interest, dividends, or gains in a regular 401(k) each year. These earnings are tax-free until you take them out. If you received a distribution, it'll be reported on Form 1099-R. All (gains and bonuses) must be included on your tax return. For a Roth 401(k), contributions are made with after-tax dollars, and qualified distributions, including interest, are tax-free.
For additional information, see a IRS Retirement Plans 🔗 Individual Retirement Arrangements (IRAs)