You can determine the "break-even point" -- when the value of the larger checks exceeds the cost of forgoing the earlier benefit -- by using Social Security's benefit estimator. In the above example, you would first calculate how much your mom would take home in the 48 months between age 62 and age 66 if she chose the smaller benefit (\$350 times 48 equals \$16,800). Then you'd compare the difference in monthly payments at age 62 and age 66 (\$500 minus \$350 equals \$150), and divide the amount from the first calculation by that amount (\$16,800 divided by \$150 equals 112 months, or a little over 9 years). So if Mom lives past 75 (age 66 plus 9 years), she'll earn more overall by delaying.

If your mom waits until her own full retirement age to claim spousal benefits, she can benefit from another technique. If her spousal benefit is larger than her own benefit, she can get spousal checks for the years between her full retirement age and age 70. Then, once her own benefit has hit its maximum amount, she can switch from spousal benefits to a benefit based on her own record if that amount is greater.

If there's a dependent child in the mix, the rules change a bit. Your mom can receive a full spousal benefit -- up to half of her husband's full retirement benefit -- at any age, as long as her husband has filed for Social Security and the child is receiving benefits. (The children of Social Security recipients qualify for checks as well, as long as they're unmarried and under 18, or under 20 and full-time students, or disabled with a disability that started when they were younger than 22.) Your mom can receive her spousal benefit until the child reaches age 16. At that point, the child's benefits would continue but your mom's would stop unless she's old enough to receive retirement benefits (age 62 or older) or survivors' benefits as a widow or widower (age 60).

Your mom is divorced. Your mom can claim benefits based on her ex's record as long as:

• She's at least 62.
• The marriage lasted at least 10 years.
• She's currently unmarried.

What's more, her ex doesn't have to cooperate. As long as he's 62 or older, he needn't have filed to receive his own benefits for her to claim a spousal check, and his approval isn't needed. It will help the application process if your mom has his Social Security number, but the Social Security Administration says it can track down his records without it.

The benefit amount and rules for collecting are the same for a divorced spouse as for a current spouse. As noted above, claiming a spousal benefit doesn't reduce the ex's benefits, or affect the benefits of his current spouse or any other former spouses. But as with other retirement benefits, choosing to take the money early will result in a permanent reduction in your mom's checks. If she continues to work, the check could be reduced further by the earnings test.

If she delays claiming her spousal benefit until she reaches her own full retirement age, she'll also preserve the choice to switch to her own retirement benefit at age 70, if that amount is greater.

What if your mom remarried after her divorce? She can't claim benefits based on an ex's record if she's still married to a subsequent spouse. But if the later marriage ends -- by divorce, annulment or death -- she can apply for benefits based on either previous spouse's record.