To become eligible for Social Security benefits in retirement, you need to earn money and pay into the system via payroll taxes during your working years. Your earnings render you eligible for work credits, and you can accrue a maximum of four of those per year.

It takes 40 work credits to collect Social Security in retirement based on your own earnings record. But if you didn't work at all or you didn't accumulate enough work credits to be eligible for Social Security on your own, you may still be able to get benefits if you are, or were, married to someone who's eligible.

It's a concept known as spousal benefits. And to be clear, spousal benefits can be a lifeline for seniors who otherwise would not get Social Security on their own.

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But even if you are entitled to a monthly income from Social Security based on your own earnings history, you can still collect spousal benefits. You just can't collect more than one retirement benefit from Social Security at once.

How spousal benefits work when you're entitled to your own benefit

Spousal benefits are worth 50% of what your current or former spouse receives in Social Security, provided you wait until full retirement age to sign up for them. This means that if your spouse is eligible for a $3,000 monthly Social Security benefit, you'd get a $1,500 monthly spousal benefit at full retirement age.

If you're also entitled to your own Social Security benefit based on your personal wage history, you can collect that benefit or collect a spousal benefit. But you can't double up and get both as separate benefits. But the good news is that Social Security will make sure you get the highest amount you're entitled to.

So let's say that based on your own work history, you're eligible for a monthly Social Security benefit of $1,600. If your spousal benefit would amount to $1,500, you'd just stick to your own benefit, since it's the higher-paying option. But if your own benefit is only $1,400, then you'd be eligible for a $100 bump-up, so you're getting the full sum you're eligible for.

Now, another thing you should know is that while you can grow your personal Social Security benefit by delaying your filing past full retirement age, you cannot grow a spousal benefit. So that's something to consider as well.

Know the rules

Social Security spousal benefits can be a little complicated when you don't know how they work. If you're in a position to collect spousal benefits, it's important to read up on the rules, even if you're already eligible for a benefit of your own.

You should also know that if you're married, you'll have to wait for your spouse to sign up for Social Security before you're eligible for spousal benefits. But if you're divorced, you don't necessarily have to wait on your ex-spouse to file. So it's a good idea to dive into the topic of spousal benefits if you're in any sort of position to be able to collect them.