via MSN Money/ Marketwatch

An important deadline is fast approaching for people required to tap their retirement savings for the first time. And at least one set of numbers indicates that many investors could miss it.

If you turned age 70½ at any point in 2014, you must take — by April 1 of this year – your first “required minimum distribution” from your retirement accounts – generally those with tax-deferred contributions. These include, among others, IRAs, 401(k)s, 403(b)s and 457(b)s.

(There are two exceptions. The rules don’t apply to the original owners of Roth IRAs. And if you continue to work beyond age 70½, you can generally delay withdrawals from your employer’s retirement plan until after you retire.)

As the term indicates, RMDs are the minimum amounts that the owner of a retirement account must withdraw annually. But rules regarding the deadline for the initial withdrawal often confuse people.

Normally, annual withdrawals must be made by Dec. 31. But with the first distribution, the Internal Revenue Service gives you some extra time: You have – if need be – until April 1 of the year following the calendar year in which you turn 70½ to take your first RMD. (Of course, you don’t have to wait until April 1; you can take the RMD before that deadline.)

There’s also the added confusion of the April 15 deadline for filing tax returns. Some people invariably mistake April 15 as the deadline for their first RMD.

At Fidelity Investments – as of Dec. 26, 2014 – fully 59% of the company’s investors eligible to take their first RMD from their IRA in 2014 hadn’t yet taken the full amount required. More worrisome, of those, 43% hadn’t taken any RMD to date for the year.

Translation: Many investors, according to Kim Reingold, a spokeswoman for Fidelity, “continue to leave themselves vulnerable to significant tax penalties when their withdrawals aren’t made in a timely fashion.”

How significant? According to the IRS, “If an account owner fails to withdraw a RMD, fails to withdraw the full amount of the RMD, or fails to withdraw the RMD by the applicable deadline, the amount not withdrawn is taxed at 50%.”

In short, if you’re required to take your first distribution from a retirement savings account by April 1 and haven’t done so, you need to act quickly. You can calculate the size of your RMD using, among other resources, a Fidelity calculator (which also has a link to additional information about RMDs) or worksheets on the IRS website. The IRS website also has a good guide to RMDs and to frequently asked questions about such withdrawals.

(Note: If you have multiple IRAs, you should calculate the RMD separately for each account – but you can withdraw the total amount from a single IRA. That said, if you have different types of retirement plans – such as an IRA and 401(k) – RMDs must be taken separately from each kind of plan.)

And, of course, contact your IRA custodian or retirement-plan administrator. They’re waiting to hear from you.

AccountingImportant April 1st Deadline for Retirement Account Holders