One of the hardest financial decisions you might have to make in the course of retirement planning isn't deciding when to resign from your job or start tapping your savings. Rather, it's when to claim Social Security benefits.

You're allowed to start taking benefits at any point once you turn 62. If you want your monthly checks without a reduction, though, then you'll need to wait until you reach full retirement age, which is 67 if you were born in 1960 or after.

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You can also delay Social Security past full retirement age to boost your monthly checks. You'll earn delayed retirement credits worth 8% per year you delay beyond that point, up to age 70.

Of course, waiting until 70 to file for Social Security isn't necessarily easy. It could mean working longer or tapping your retirement savings more than you'd like to cover your living costs.

But new data shows there's a real upside to delaying Social Security until age 70. It also reveals that few claimants take advantage of that key opportunity.

What you might gain by delaying Social Security until age 70

Only about 10% of Social Security recipients claim benefits at 70, according to findings from the National Bureau of Economic Research. But the group's data reveals that more than 90% of Americans ages 45 to 62 can benefit from waiting that long.

The data also shows that by not waiting, people in this cohort could lose out on a median of $182,370 of household lifetime discretionary spending. Ouch. Not only that, but the research shows that optimizing Social Security could lead to a 17% gain in lifetime spending for 25% of claimants ages 45 to 62.

So why do so many people claim Social Security sooner? For some, it's a matter of wanting to exit the workforce earlier. For others, it may be because they can't continue working despite wanting to, whether due to health reasons or difficulty maintaining employment.

But either way, the data paints a pretty clear picture: For those who can wait on Social Security, sitting tight until 70 could yield a significant payoff.

Should you wait until age 70 to claim Social Security?

While there can be significant financial benefits to claiming Social Security at 70, it's not necessarily the right choice for everyone. And a big reason not to file for benefits that late is if you have poor health and don't expect to live a long life.

In that case, filing for Social Security at 70 could mean shorting yourself on lifetime income despite locking in larger monthly checks. If you're not confident in your own longevity, it could even make sense to claim Social Security early.

It may also not make sense to claim Social Security at 70 if you want to end your career sooner and have a nice amount of savings to fall back on.

As you age, your health and mobility could decline. If you don't need your Social Security income to cover basic retirement expenses but you do need your benefits to afford travel or other things you've always wanted to do, you shouldn't necessarily deny yourself those opportunities to boost your monthly checks.

But all told, delaying Social Security until age 70 could make a huge difference in your spending power throughout your senior years. And it could make an even more meaningful difference if you don't see yourself building up a significant amount of retirement savings in your lifetime. So it pays to think about whether a delayed Social Security claim is possible and what it might do for you.