Social Security is the largest federal program in the United States. About 66 million Americans receive benefits each month, and those payments will total more than $1 trillion this year. On top of that, another 182 million Americans currently work jobs covered by Social Security, which means they will probably receive benefits in the future.

Like many federal programs, Social Security is full of nuanced rules and caveats that can make the program tricky to navigate. Here are three easily avoided mistakes that could cost retirees and their spouses a fortune.

Social Security benefits application form covered with by a calculator, a pen, and a pair of glasses.

Image source: Getty Images.

1. Claiming Social Security retirement benefits too early (or too late)

The size of your monthly Social Security check depends on two things: your average earnings during the 35 highest-paid years of your career and the age at which you claim retirement benefits.

Eligibility for Social Security starts at age 62, even if you are still working. But you are not eligible to receive the full benefit (also called the primary insurance amount, or PIA) until you reach full retirement age (FRA). Claiming Social Security before FRA will result in a permanent reduction of benefits of up to 30%, though the exact reduction depends on how early you receive your first check.

The chart below shows the FRA for individuals born after 1942.

Year of Birth

Full (Normal) Retirement Age

1943 to 1954



66 and 2 months


66 and 4 months


66 and 6 months


66 and 8 months


66 and 10 months

1960 and later


Source: Social Security Administration.

Alternatively, delaying Social Security beyond FRA results in a permanent increase in benefits of 8% per year, though these delayed retirement credits stop accruing at age 70. In other words, retired workers can maximize their Social Security checks by waiting until age 70 to claim benefits, but delaying any further serves no purpose.

This calculator for retired worker benefits shows how early or delayed retirement will affect Social Security payments.

2. Misunderstanding Social Security spousal benefits

The spouse of a retired worker might also be eligible for Social Security based on that worker's earnings, but spousal benefits are calculated a little differently. Most notably, spouses can receive up to 50% of retired workers' PIA, but the amount spouses actually receive each month depends on the age at which they claim benefits.

Here again, eligibility starts at age 62, and like the benefits paid to retired workers, spousal benefits will be permanently reduced if spouses claim Social Security prior to FRA. But in this case, there is no credit for delaying benefits beyond FRA. That means nonworking spouses can maximize their Social Security checks by starting benefits in the month they reach FRA. It never makes sense to wait longer.

Of course, not everyone can afford to delay until FRA. This calculator for spousal benefits shows how early retirement will impact Social Security payments.

3. Missing the Medicare enrollment period

Generally speaking, Medicare is a government-sponsored health insurance program for individuals age 65 or older. Social Security beneficiaries are automatically enrolled in Medicare Part A (inpatient insurance) and Medicare Part B (outpatient insurance), and coverage typically starts on the first day of the month in which they turn 65. But seniors who have not yet claimed Social Security at age 65 will have to complete this Medicare application.

In that scenario, your Initial Enrollment Period (IEP) starts three months before the month in which you turn 65, and it ends three months after the month in which you turn 65. For example: If your 65th birthday is in June 2023, your IEP runs from the beginning of March 2023 through the end of Sept. 2023.

Medicare Part A is free for seniors that have paid Medicare taxes for at least 10 years, but you will have to pay a premium for Part B, and that premium goes up if you sign up late. Specifically, if you miss your IEP, you typically have to wait until the next General Enrollment Period, and you'll have to pay a monthly late enrollment penalty of 10% (based on the standard Medicare Part B premium) for each full year you failed to sign up. To make matters worse, you have to pay that penalty for as long as you're enrolled in Medicare Part B.