If you turn 70 1/2 this year (2013) and will take your first minimum withdrawal this year, here's what you need to know:

Say you'll still be 70 at year end of 2013. You must take your Dec. 31, 2012, IRA balance — say it's $200,000 — and divide it by 27.4. (That's the joint life-expectancy figure for two people age 70 and 60. To figure out your divisor, see our calculator below.) The result is $7,299. You would then take out at least that amount by 12/31/13, and have fulfilled your initial minimum withdrawal requirement. Not too difficult, right?

Now let's say you'll be 71 at the end of this year (2013). In this case, the proper divisor is 26.5 years. Your minimum withdrawal number is $7,547 ($200,000/26.5). So you'd take out that amount (at least) on or before Dec. 31, 2013. Simple enough.

There's only one exception to the preceding arithmetic. This is when your spouse is designated as the sole beneficiary of your IRA and he or she is more than 10 years younger than you. In this case, use Table II in Appendix C of IRS Publication 590 (Individual Retirement Arrangements) to find your divisor, which will be based on your age and your spouse's age as of Dec. 31, 2013. You'll get an even lower minimum withdrawal amount than you would by following the "standard" procedure in the preceding example. And lower is good, since it means lower taxes. Again, take out the calculated amount (at least) on or before Dec. 31, 2013.

Next year (2014) you must take your second minimum withdrawal by Dec. 31, 2014. That amount will equal your Dec. 31, 2013, IRA balance divided by the joint life-expectancy figure based on your age at the end of next year.

You'll take your first minimum withdrawal next year

If this is really what you want to do, the answer is easy. You must take your initial minimum withdrawal by April 1, 2014. For 2013, you have nothing to worry about. Remember, however, if you go this route you must also take your second minimum withdrawal by Dec. 31, 2014, and this means two tax hits in 2014. If you have a big IRA, this double whammy could easily push you into a higher tax bracket, which clearly isn't a joyful occasion. So you may want to reconsider taking your first minimum withdrawal by the end of this year (2013) instead (see above).

See table below.