Self-Employed Retirement Plans Estimate the maximum contribution amount for a Self-Employed 401(k), SIMPLE IRA, or SEP. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Have A Question About This Topic? Name Email Address Question Thank you! Oops! Related Content Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates. What If You Get Audited? The chances of an IRS audit aren't that high. And being audited does not necessarily imply that the IRS suspects wrongdoing. Where Will Your Retirement Money Come From? Retirement income may come from a variety of sources. Here's an overview of the six main sources.