G

As you approach retirement, there are two concepts that are critical to understand if you want to make an informed decision about when to apply for Social Security benefits.

The first is your primary insurance amount. I've discussed this elsewhere, so I won't go into detail about it here. All you need to know for present purposes is that this is the amount you'll receive in Social Security benefits if you wait until reaching your full retirement age before applying for them.

This brings us to the second concept: your full retirement age. According to the Social Security Administration, this is the "age at which a person may first become entitled to full or unreduced retirement benefits" -- in other words, your primary insurance amount.

The full retirement age for those in or near retirement is around 66. Anyone who eligible to apply for benefits over the next few years is entitled to unreduced benefits starting at that age. Here's a more detailed breakdown of the full retirement ages:

Year of Birth

Full Retirement Age

1937 or earlier

65

1938

65 and 2 months

1939

65 and 4 months

1940

65 and 6 months

1941

65 and 8 months

1942

65 and 10 months

1943-1954

66

1955

66 and 2 months

1956

66 and 4 months

1957

66 and 6 months

1958

66 and 8 months

1959

66 and 10 months

1960 and later

67

Source: Social Security Administration.

But this hasn't always been the case. As you can see in the table above, when the Social Security program was first introduced in the 1930s, the full retirement age was 65. It was subsequently raised in two-month increments between the years of 1938 and 1942 to the age of 66 for future beneficiaries born between 1943 and 1954.

And the adjustments haven't stopped. In response to the system's near-insolvency in the early 1980s, Congress voted to increase the full retirement age once more. As before, there is a period in which the changes will be gradually phased in. But anyone born in 1960 or later won't be eligible to receive unreduced benefits until they turn 67.

At first glance, this seems to factor heavily into a decision about when to apply for benefits. If you do so before reaching your full retirement age, then your monthly check will be permanently reduced depending on how early you take it. By contrast, if you wait until turning 70 to apply, then your benefits could be as much as 32% larger than your primary insurance amount.

You can see this in the chart below, which assumes a full retirement age of 66:

G

Here's how the Social Security Administration explains it in the pamphlet "When to Start Receiving Retirement Benefits":

If you live to the average life expectancy for someone your age, you will receive about the same amount in lifetime benefits no matter whether you choose to start receiving benefits at age 62, full retirement age, age 70, or any age in between.

The point here is twofold. On one hand, it's important to know what your full retirement age is, as this will help to inform your decision about whether you want to apply before or after reaching full retirement. On the other hand, whenever you choose to claim benefits, there's little reason to second guess your decision.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.