Tax basis in IRA


Q. I am a retired government worker who has contributed the maximum amount to the Thrift Savings Plan. After being retired for several years, I transferred the TSP to a traditional IRA. If I convert the traditional IRA to a Roth IRA, how do I figure my “basis” in the IRA to determine the amount that is taxable?

A. If the only thing you ever put into the IRA was your traditional TSP assets, then the account has no tax basis and is all taxable upon distribution (or conversion). If you have contributed nondeductible or other after-tax money to the IRA, you’ll need to figure out how much. That’s your tax basis. You should consult a CPA for help if this is the case.


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Mike Miles is a Certified Financial Planner licensee and principal adviser for Variplan LLC, an independent fiduciary in Vienna, Virginia. Email your financial questions to and view his blog at

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