Many people grumble about the fact that they're required to pay Social Security taxes on their income. But those taxes serve a purpose -- funding the program so that it's there for you once you're ready to retire. Furthermore, by earning money and paying Social Security taxes on your income, you make yourself eligible for benefits once your time in the workforce comes to an end.

But even if you never worked and never paid a dime into Social Security, you might still be eligible for benefits from the program. Here's how.

Spouses get special allowances

If you're married to someone who's eligible for Social Security benefits, you'll generally be entitled to what are known as spousal benefits. These have special rules that differ from regular benefits. But all told, they offer you an opportunity to collect Social Security, even if you never paid into the program during your lifetime.

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The spousal benefit you're able to collect will hinge on what your spouse is eligible for. If your spouse is entitled to a monthly benefit worth $2,000, you'll be in line for a $1,000 benefit, provided you wait until you reach your full retirement age to sign up.

You can't start collecting your monthly spousal benefit until your spouse files for Social Security. If your spouse decides to delay their claim, you'll have to sit tight.

Furthermore, while delaying Social Security can boost your monthly benefits if you're filing based on your own earnings record, you can't grow a spousal benefit by holding off on claiming it past full retirement age. If you're entitled to your full spousal benefit at age 67, you might as well sign up at that point.

Spousal benefits apply to divorcees, too

One of the nicest thing about spousal benefits is that you don't have to still be married in order to collect them. If you were married to someone for 10 years or more and they're eligible for Social Security, you can claim a spousal benefit on their record if you're divorced. And you generally don't have to wait for your ex-spouse to claim Social Security to get those benefits yourself.

A great option to fall back on

Spousal benefits allow people who never worked to collect Social Security in retirement. But you may still want to claim a spousal benefit, even if you did work.

Let's say your spouse earned a high salary during their career and is therefore eligible for a monthly Social Security benefit of $2,500. Meanwhile, let's say you were a lower earner, so the benefit you're entitled to, based on your wage history, is $1,100. In that case, you can opt to collect a spousal benefit instead of your own benefit, and that would leave you with $1,250 a month.

To be clear, though, you can't collect a spousal benefit on top of your own benefit. The Social Security Administration won't let you double dip like that.

It pays to read up on Social Security spousal benefits if you're worried you didn't earn enough and pay enough Social Security tax in your lifetime to qualify for retirement benefits. You may be surprised at how much income you're actually eligible to collect.