Social Security is the largest social program in the country, providing income to tens of millions of Americans each month that helps them cover the cost of living in retirement. Needless to say, it's also one of the most complex public programs, given its magnitude and the fact it funds other recipients beyond retired workers.

One of these groups is spouses, who are able to claim Social Security benefits based on their partner's work history. Here are three key aspects of the spousal benefit that all retired couples should know.

1. Who is eligible? How much in benefits can they claim?

Typically, people qualify for spousal benefits if they have been married for at least one year to someone who is collecting their own Social Security retirement benefits. Those caring for a child under the age of 16 or a child receiving Social Security disability benefits may also be eligible.

These rules allow non-working or lower-earning spouses to still receive Social Security in cases when they qualify for little to no benefits on their own.

How much a spouse will actually receive is determined by two factors. First is their partner's primary insurance amount (PIA), or the benefits the partner is entitled to claim at their full retirement age (FRA), which is 67 for those born in 1960 or later. Spousal benefits can be worth as much as half of their partner's PIA.

The second factor is timing. A spouse can claim Social Security as early as age 62, but the earlier they claim, the less in benefits they will ultimately receive. For instance, claiming spousal benefits immediately when turning 62 would reduce the benefit amount to as little as 32.5% of their partner's PIA.

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2. You may prefer the spousal benefit to your own

Remember, Social Security benefits are based on how many years a person has worked and how much they made throughout their career. In cases when someone qualifies for both retired worker and spousal benefits, they only have to file once, and the Social Security Administration (SSA) will effectively pay the higher of the two benefit amounts.

In practice, both benefits will actually be paid in cases where the spousal benefit is worth more. For instance, let's say a retiree qualifies for $1,000 of Social Security based on their work history, but their spousal benefit is worth $1,200. The SSA will first pay out the $1,000, and then an additional $200 will come from the spousal benefit to ultimately add up to the higher of the two amounts.

3. Divorcees can still claim spousal benefits

People who have divorced their partner may still be able to qualify for a spousal benefit based on their ex-partner's work history. However, there are some requirements to be aware of. As a divorcee, they would only qualify for the spousal benefit if they had been married for at least a decade. If the ex-partner is not yet collecting Social Security, the divorce must've occurred at least two years before spousal benefits will be paid.

Additionally, a divorced individual must remain unmarried to receive the spousal benefit based on their ex-partner's record. Once remarried, they would get the spousal benefit, if applicable, tied to their new partner. That said, the ex-partner remarrying does not affect the former spouse's ability to claim benefits.