NOTE: The people claiming the funds of all IRA funds are considered as an aggregate may be mixing up a rule instituted 1/1/2015 that stated for doing rollovers, all the funds are considered as one for the sake of counting the frequency of rollovers – ie: you can rollover from any IRA/401k once in 12 month period, but you can’t rollover from IRA#1 and IRA#2 within a 12 month period, but could rollover IRA#1 and 12 months later rollover from IRA#2.
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ucodegen-
Every time I’ve looked into this issue, competent sources all point to the fact that all IRAs are considered in terms do what is taxable when rolling over traditional IRA to Roth IRA.
Example below from Forbes (Forbes always looks for tax avoidance angles)..
“The backdoor Roth works well when an individual doesn’t have any other tax-deferred money in any other IRA – including traditional, SEP and SIMPLE IRAs. However, if you have other assets that are tax deferred in that IRA or another, then you could run into a potential tax blunder if you aren’t careful. When you convert an IRA to a Roth IRA, you’re converting a proportional share of the conversion amount as non-deductible and deductible contributions across all of your IRAs. So, in essence, you need to account for all of your IRA assets when doing a conversion to make sure you’re paying the right amount of taxes. “
On the other hand, If the money is rolled from a 401k to Roth IRA I believe there is a way to select the after-tax only portion for rollover.
