For those over 70 1/2, with IRAs, keep a close watch on those RMDs. Last year was a banner year for stocks. As a result, retirement funds with allocations tilted toward equities will need to be evaluated for purposes of RMD.
The RMD withdrawal is based on your total IRA balance as of 12/31/2017 times the multiplier for your age. For a senior in the second year of RMD, that's 3.77%. Folks with a large exposure to equities in 2017 will need to do the math.
The sneaky part is the IRA balance. For folks with top-heavy equity accounts in IRAs, make sure you re-calculate your balance subject to the RMD.