The only place where you need to combine the values of these IRAs is where TurboTax asks you to enter the combined year-end value of all of your traditional IRAs, so yes, you'll need to add these values together yourself. For Form 8606 to be prepared correctly, this value must be accurately entered. Because you have a balance in traditional IRAs that is likely to be substantially above the amount of basis you have in nondeductible traditional IRA contributions, a small portion of each year's distributions from your traditional IRAs (no matter which IRA the distribution comes from because all of your traditional IRAs are treated as one) will be nontaxable, consuming an equal amount of your basis.
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