The 50 percent tax penalty that's easy to dodge

Missing the deadline to take money from your retirement accounts could trigger a nasty 50 percent tax penalty. Emphasis on "could."

Under IRS rules, so-called required minimum distributions (aka RMDs) generally kick in on IRAs once you reach age 70½. For 401(k) plans and other defined contribution plans, it's typically when you turn 70½ or you retire, whichever is later.

The deadline to take a particular year's RMD is Dec. 31 of that year. But in the year you're first required to take an RMD, you have until April 1 of the following year to make that withdrawal.

If you have cash in your account, Fidelity says you can take that withdrawal "any day of the week" — including the deadline itself, Saturday. Need to make a trade? You're likely too late.

(For more of the ins and outs on RMDs, including how to figure out how much to take, see our guide here.)

If you miss the deadline — by a few days or a few months — don't panic. The IRS has been lenient about retirees who forget to take their RMD, said Maura Cassidy, vice president of retirement at Fidelity.

Do take yours for 2016 as soon as possible. Then file a Form 5329 with your tax return this year, Cassidy said.

"Attach a letter explaining why you missed taking it last year," she said. "Usually the IRS has waived the penalty."

Procrastinators should also start strategizing about ways to cut next year's tax bill, said certified public accountant Benjamin Tobias, president of Tobias Financial Advisors in Plantation, Florida. Even if the grace period has you taking your first RMD this spring, you'll still need to take your RMD for 2017 by Dec. 31 — and two in one year could make a big impact, he said.