Does an inherited IRA count toward the backdoor Roth pro-rata rule?

Usually, no. A non-spousal inherited IRA generally does not count toward the backdoor Roth pro-rata rule for your own IRAs.

The pro-rata rule looks at your year-end balances in traditional, SEP, and SIMPLE IRAs that you own. A typical inherited IRA from someone other than your spouse stays a separate account and is not combined with your own IRA balances for that calculation.

That is why many taxpayers with an inherited IRA can still do a relatively clean backdoor Roth, as long as they do not also have pre-tax money sitting in their own traditional, SEP, or SIMPLE IRAs at year-end.

Why this matters:

• If you have pre-tax money in your own traditional IRA, the pro-rata rule can make part of the conversion taxable
• If the only extra IRA is a non-spousal inherited IRA, it is generally treated separately
• If you inherited an IRA from your spouse and elected to treat it as your own, that is different, and it can become part of your own IRA balances

Publication 590-B explains that basis in an inherited IRA stays with that inherited IRA and cannot be combined with basis in your own traditional IRAs unless special spousal rules apply. In plain English, inherited IRA money usually does not contaminate your backdoor Roth calculation, but your own pre-tax IRA balances still do.

Because IRA titling and inherited IRA elections matter here, double-check how the account is registered before filing Form 8606.