Typically, the money invested in a Roth IRA or Roth 401(k) is post-tax, meaning you've already paid the taxes on the amount contributed. An extreme example of this is investor and Palantir Technologies founder Peter Thiel, who grew a Roth IRA from $2,000 to about $5 billion in about two decades. Rules of conversion Converting assets to a Roth IRA can get around some of the other limitations on the accounts. Investors should also consider the bill they'll have by converting assets into a Roth IRA now. It also usually only makes sense to do a Roth conversion if you see your tax rate increasing in the future.

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