Either way, the assets grow tax-deferred and withdrawals are taxed as ordinary income, not capital gain.

FORBES: IRA Tips and Traps

In earlier research, Mr. Mahaney highlighted another benefit to deferring benefits until later: If you expect much of your retirement income to come from tax-deferred savings, you might be better off using those assets first and delaying all, or a large chunk, of your Social Security.

WSJ: Family Value: Bolstering Your Social Security Benefits