RMD Math for Retirement Plans
Based on current IRS life expectancy tables, the 2013 RMD from most retirement plans is based on the account owner’s age as of their 2013 birthday and account balance as of December 31, 2012.
These IRS tables change infrequently. The only retirement plans not covered by these tables are 401(k) plan participants who are still working, Roth IRA owners. These same tables cover retired Roth 401(k) owners but their withdrawals are almost always tax free.