If you've been socking away money into a regular individual retirement account, you're probably staring at a sizable stash. Which leads to a very important question: When can you get your hands on it?

The short answer is: Whenever you want.

The smart answer is: Hold off as long as you can.

There are two critical ages with a regular IRA. At 59½, the government allows account owners to make withdrawals without penalties. You can take as much or as little as you like -- whenever you like. At the end of the year, you simply pay income tax on the money you withdrew.

At the age of 70½ (defined in government speak as "the April 1 following the year you turn 70½"), you must start taking money out of your regular IRA. That's because the government doesn't get its money -- income tax -- until you make withdrawals from your account, and it wants to give you plenty of time to spend every dime.

If you have a Roth IRA -- in which the tax was paid before the money went into the account -- no such rules apply. You can keep building a Roth for as long as you like.

Before 59½
Many people don't realize that the government also will allow you to take money out of a regular IRA without penalty before the magic age of 59½. There are about a dozen reasons that the government will let you access the money, such as disability, higher education expenses and first-time homeownership. The bad news: The rules are very rigid. You must carefully document your reasons for early withdrawal or face hefty IRS penalties.

You also can take the money out early without having to meet one of the exception circumstances as long as you take it out in regular amounts. This is known as the substantially equal periodic payment method. Once you start withdrawing using this method, which is based on IRS-established life-expectancy tables, you must continue taking them for at least five years even if you reach 59½ in the interim.

But probably the greatest risk is that the earlier you start dipping into an IRA, the greater the risk of outliving it.

RULE 1: At any age, before you set up a plan to take money out of your IRA, do your homework. Unless you've got some major financial know-how, this is not the time to go it alone. Get a trained financial planner and a tax specialist to walk you through the pros and cons. Make sure you feel comfortable with the advice and get a second opinion, if you can.

RULE 2: Look at the long term. People are living longer, healthier lives. But the cost of health care and elder care has skyrocketed. If you tap into the IRA now, are you going to be broke when you reach your 80s or 90s?

This magic moment -- 70½
If you're nearing 70½, the government has some good news for you. While you are required to start taking regular disbursements from your regular IRA account, the IRS has made the rules a lot simpler. The agency modified its life-expectancy tables to reflect longer lifespans. That means the required disbursement, the amount the government says you have to withdraw each year, is smaller.

If you take only this minimum amount every year, it will be nearly impossible to outlive your retirement account. You do have, however, the freedom to take more out if you like.

"This changes it for the better for everyone," says Barry Picker, CPA, certified financial planner and the author of "Barry Picker's Guide to Retirement Distribution Planning." And by taking minimum disbursements, he says, "you can never run out unless your investments are so bad that the account drops under the minimum distribution."