Social Security can be worth more—a lot more, and not just foryou but for your spouse—depending on when and how you claimbenefits. It can also cost you both.

Related: Simple quiz can predict earlyretirement

Couples claiming Social Security benefits need to considerseveral factors, Fidelity says, when deciding when to start thechecks coming in: their life expectancy, any age difference, andtheir overall health.

Related: 10 worst states for well-being inretirement

Failing to do so could cost them big time—or could cost thesurviving spouse years later—while a little planning andwillingness to postpone claiming benefits as soon as eligible couldpay off with bigger checks for many years.

While many people are eager to claim benefits as soon as they’reeligible at age 62, that means they’re going to get a reducedbenefit. And they’ll get that reduced benefit for the rest of theirlives.

But if they wait till they’re closer to age 70, those checkswill be up to 8 percent larger for every year they don’t claim;that means a much bigger check when they finally do apply forbenefits.

But of course that won’t do much good if one or the other of youhas health issues or comes from a family with shorterlifespans—better to have the money now and enjoy retirement.

For instance, did Great-Aunt Martha live to be 98, or did UncleGeorge not even make it to 40? Do either or both of you have healthconditions that could shorten your lifespan?

Postponing claiming benefits if you’re not likely to live longenough to enjoy them doesn’t make much sense, and the spouse with alikelihood of a shorter lifespan might be better off claiming assoon as eligible.

One or the other of you would have to live into your late 80sbefore you received as much money as you would have had if you hadclaimed benefits at age 62—so if that kind of longevity’s notlikely, claiming as soon as you’re eligible could be the bestoption.

Then there’s the issue of a big pay difference betweenspouses.

The higher-earning spouse might want to postpone claiming aslong as possible to grow the benefit for the lower-earningspouse—particularly if there’s a substantial age difference betweenthem.

If the high earner is much older, the lower-earning spouse willbe dependent on the survivor check for a long time, so it makessense to try to increase its value.

The strategy here is for the lower-earning spouse to claim onhis or her own work record, and switch to the higher-earningspouse’s record later—when the high earner turns 70, for instance,or as a survivor benefit when the high earner dies.

If you’re both close to the same age and have similar lifeexpectancies, you’re both likely better off postponing claimingbenefits as long as possible, since that will result in higherbenefits for each spouse—for the rest of your lives.

Maximizing benefits this way lessens the likelihood that you’llrun out of money during retirement.