The choice of when you'll start collecting Social Security could be a $100,000 decision, and making the right call requires both a bit of math and a dash of luck. That's because the age at which you begin taking your benefits affects the size of your monthly checks. This, coupled with how long you live, will determine how much you receive from the program overall. 

Below, we'll take a look at how this works in practice, and how that can inform your decision about when to file for Social Security.

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Image source: Getty Images.

Why the age you begin Social Security matters

You can start taking Social Security any time after you turn 62. Once you do, the government will send you checks monthly for the rest of your life, however long that may be. But if you want what the program considers your "full" benefit (based on your salary history), you must wait until you hit your full retirement age (FRA) to apply. That's 66 for those born between 1943 and 1954. Then, it rises by two months every year thereafter until it hits 67 for those born in 1960 or later.

For every month shy of your FRA that you are when you apply to take benefits, the size of all your future payments gets reduced by a fraction of a percent. Those fractions can add up: If your FRA is 67 and you take benefits at 62, you'll only get 70% of your full benefit per check. If your FRA is 66, claiming at 62 would shrink your checks to 75% of your full benefit. But claiming sooner means getting more individual checks, even if they are for smaller amounts.

On the other side of the coin, you can also delay taking benefits past your FRA. That will make your monthly checks progressively larger until you reach your maximum possible benefit at 70. That's 124% of your full benefit if your FRA is 67 or 132% if your FRA is 66.

To illustrate how those different scenarios might play out, consider the following chart. It assumes you have an FRA of 67 and qualify for the current average benefit of $1,522 per month at that age. Here's how much you would have received by the end of each year if you began claiming benefits at 62, your FRA, and 70. 

Sum Total of Social Security Payments Received

Age

Claiming at 62

Claiming at 67

Claiming at 70

62

$12,785

$0

$0

63

$25,570

$0

$0

64

$38,355

$0

$0

65

$51,140

$0

$0

66

$63,925

$0

$0

67

$76,710

$18,264

$0

68

$89,495

$36,528

$0

69

$102,280

$54,792

$0

70

$115,065

$73,056

$22,647

71

$127,850

$91,320

$45,294

72

$140,635

$109,584

$67,941

73

$153,420

$127,848

$90,588

74

$166,205

$146,112

$113,235

75

$178,990

$164,376

$135,882

76

$191,775

$182,640

$158,529

77

$204,560

$200,904

$181,176

78

$217,345

$219,168

$203,823

79

$230,130

$237,432

$226,470

80

$242,915

$255,696

$249,117

81

$255,700

$273,960

$271,764

82

$268,485

$292,224

$294,411

83

$281,270

$310,488

$317,058

84

$294,055

$328,752

$339,705

85

$306,840

$347,016

$362,352

86

$319,625

$365,280

$384,999

87

$332,410

$383,544

$407,646

88

$345,195

$401,808

$430,293

89

$357,980

$420,072

$452,940

90

$370,765

$438,336

$475,587

Source: Calculations by author based on $1,522 monthly benefit at 67. All figures are rounded to the nearest dollar.

As you can see, the right time for you to begin Social Security will depend largely on how long you expect to live. If you die before 78, you'd get more money from the program overall by claiming Social Security at 62, but if you live past 82, then delaying until 70 will get you the most money. And the longer you live, the more significant the difference becomes. If you make it to 90, waiting until 70 to start would net you over $100,000 more from the program than you would have gotten if you'd started benefits at 62. And that doesn't even factor in the possibility that by working longer, you could be adding more high-earning years to your work history, which would increase the size of the full benefit all those other percentages are based upon.

How to decide when you should begin Social Security

The first question you must ask yourself when deciding when to begin Social Security is what you want to get out of the program. Your goal may be to get the most money possible. Or, you may want to use your checks to enable you to retire early, even if that could reduce your overall lifetime benefit. You may be afraid that you're going to outlive your retirement nest egg, and want to assure yourself of the largest possible monthly checks, regardless of how long you're receiving them for. But whatever your priorities, by explicitly laying them out, you'll point yourself in the right direction.

Those who want to collect the largest total amount possible over the course of their retirement should begin by creating an account on the my Social Security website. Among the tools there is one that allows people to see estimates of what their benefits will be at various filing ages. The site uses your actual earnings from your tax returns to provide you with an accurate estimate of your potential benefits, though it assumes you'll earn roughly the same amount each year (adjusted for inflation) between now and when you begin claiming benefits, which may not be true for you.

You can then multiply your estimated monthly benefit by 12 to get your estimated annual benefit and create a table similar to the one above to see how much money you'd get with each of the different starting ages, based on how long you expect to live. 

Once you've done that, you can decide whether going for the largest lifetime benefit is a feasible strategy for you. Some people may not be able to do it even if they'd like to, because they'll need their benefits sooner to help cover their living expenses. But you may be able to find a compromise path and delay filing for a year or two past 62, which will still increase your checks, though by a smaller percentage.

Unless you plan to claim benefits now, your decision won't be set in stone. Review where you're at every few years and decide whether you'd like to adjust your plan. Just remember, if you decide to begin Social Security earlier, you may get less overall, so you'll need to increase the amount you're saving and investing for retirement to compensate.