Social Security serves as an important source of income for millions of seniors. And if you're married, you have a prime opportunity to make the most of those benefits. Here are three things you should know about Social Security if you're married going into retirement.

1. You can claim a benefit on your spouse's work record

To become eligible for Social Security in retirement, you need to accumulate 40 work credits in your lifetime. The value of a work credit can change from year to year, but if you've mostly held very part-time jobs, or if you never worked at all, then you may not have the minimum number of credits required to be eligible for benefits.

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But that doesn't mean you're totally out of luck. If you're married, you're allowed to collect a spousal benefits based on your partner's work record, and your benefit will equal up to half of what your spouse collects. If your spouse is entitled to a monthly benefit of $2,000, you may be in line for a benefit of $1,000.

Even if you did work and are entitled to Social Security benefits of your own, you may still be eligible for spousal benefits. Whether you collect them will hinge on which option pays you more -- your own benefit or half of your spouse's. Social Security will pay you the higher benefit of the two, but you can't double dip and collect your own benefit plus a spousal benefit.

2. You can't file for spousal benefits until your spouse does

If you're relying on spousal benefits to provide you with retirement income and you're still married, you should know that you're not allowed to claim them until your spouse files for Social Security. Your spouse may be eager to delay his or her claim for a higher benefit for life. But in doing so, your spouse may prevent you from getting your money sooner.

That's why it's important to create a filing strategy with your spouse. By working together, you can land on the ideal time to sign up for benefits.

3. There's no point in delaying spousal benefits

When you're claiming a Social Security benefit based on your own earnings record, it could pay to delay your filing. For each year you hold off on taking benefits beyond full retirement age (FRA), up to age 70, you'll score an 8% boost. This means that if your FRA is 67 but you delay your filing until age 70, you'll raise your benefits by 24% -- for life.

But if you're claiming a spousal benefit, the rules are very different. In fact, there's no financial incentive to delay a spousal benefit past FRA because spousal benefits can't grow. So if your FRA is 67 and your spouse is already collecting Social Security by the time you reach that age, you might as well sign up.

Read up on the rules for married couples

Being married has its advantages -- someone to not only share your retirement with, but split expenses with. If you're counting on Social Security to provide a lot of your senior income, it pays to read up on the rules for spouses so you're able to make smart choices with your benefits.