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 Pickleball in Retirement Learn about the latest sport to sweep the nation with this informative article. You May Need to Make Estimated Tax Payments If… Have income that isn’t subject to tax withholding? Or insufficient withholdings? You may have to pay estimated taxes. 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.