There is a lot more to Social Security than the retirement benefits that tens of millions of retired workers receive every month. One extremely important part of the program is known as Social Security spousal benefits.

Spousal benefits can provide much-needed retirement income to married couples where one spouse was the primary earner. This is most common in situations where one spouse was a stay-at-home parent, but they can also apply in cases where one spouse was a high earner and the other worked part-time or earned comparatively little throughout their working life.

Depending on the specific circumstances, a spousal benefit can be as high as one-half of the higher-earning spouse's full retirement benefit (formally known as their "primary insurance amount"). This means that if your spouse has a primary insurance amount of $2,500 per month based on their own work record, your spousal benefit can be as much as $1,250.

Qualifying for spousal benefits

Although the formula used to calculate Social Security benefits can be a bit complicated, the qualifications are not. This is true for spousal benefits as well. To collect a Social Security spousal benefit, there are three specific criteria that need to be met.

Older couple looking at a tablet.

Image source: Getty Images.

1. Your spouse collects a retirement benefit

First and foremost, the central requirement of a spousal benefit is that the higher-earning spouse is actively collecting their own Social Security retirement benefit. Even if you've reached your full retirement age (more on that in a bit), you can't collect a spousal benefit until the primary-earning spouse applies for their own benefit.

It's also worth noting that even divorced spouses could potentially qualify for benefits, as long as the marriage lasted for at least 10 years.

2. You are at least 62 or have a child

To collect a spousal benefit, assuming the primary earner is collecting their own benefit, you need to meet one of two requirements:

  • You must be age 62 or older
  • You have a qualifying child under 16 or who receives Social Security disability benefits

Although you can get a spousal benefit as early as age 62, it will be permanently reduced if you start receiving it before full retirement age. For Social Security purposes, full retirement age is 67 for those born in 1960 or later. If you have reached full retirement age when you start collecting a spousal benefit, it will be equal to your spouse's primary insurance amount, regardless of how old they are when they start Social Security. But if not, your benefit can be reduced by as much as 35%, depending on how early you claim.

However, if you have a qualifying child (defined earlier in this section), the spousal benefit is not reduced for early retirement.

3. You don't qualify for a larger benefit on your own work record

Finally, when you apply for Social Security, the SSA will look at your own work record and see how much you would qualify for individually, if anything. And you'll get your own benefit or a spousal benefit, whichever is higher.

To be perfectly clear, a spousal benefit is paid instead of an individual Social Security retirement benefit, not in addition to it.

A valuable part of many couples' retirement strategy

As of the latest data, 1.86 million spouses of retired workers get a benefit, with an average monthly amount of $932 -- or approximately $11,200 of annual, inflation-protected retirement income.

The bottom line is that Social Security spousal benefits provide much-needed retirement income for married couples, and as long as one spouse qualifies for Social Security benefits with their own work record, qualification for spousal benefits is straightforward.