Judging from emails and comments, plenty of people are confused about how Social Security benefits for spouses and ex-spouses are supposed to work. That’s unfortunate, since these benefits can help many people get larger checks than what their own earnings record will give them. If you are or ever have been married to someone whose earnings are substantially greater than your own, you need to know how this works.

First, some basics. Spousal and survivor benefits are based on the work record of what I’m calling the “earner” (the other spouse). You can’t get both your own benefit (based on your work record) AND a full spousal or survivor benefits on top of that. You typically get the largest benefit for which you qualify. (In some cases, you’ll get your own benefit plus an amount that together equals the largest benefit for which you qualify.)

Here are a few key points:

Spousal benefits (for current and former spouses) are based on 50% of the earner’s benefit at the earner’s full retirement age. Full retirement age is currently 66 and will be 67 for people born after 1960. If the spouse applies for benefits before the spouse’s own full retirement age, the benefit will be permanently discounted.

• If you’re currently married, the earner must have already applied for Social Security benefits for you to apply for spousal benefits. The earner does have the option to “file and suspend,” where the earner applies for benefits and then immediately suspends the application. That allows the spouse to apply for spousal benefits while the earner’s benefit can be left alone to grow.

• If you’re divorced (but were married at least 10 years and haven’t remarried), the earner needn’t have applied to start Social Security benefits but the earner needs to be at least 62. If you remarry, you can’t apply for benefits as a divorced spouse unless that subsequent marriage ends.

Spousal benefits don’t reduce what the earner receives (or what other current and former spouses may receive).

If you wait until your own full retirement age to apply, you can start receiving spousal benefits and then switch to your own benefit when it maxes out at age 70. For high earners, this “claim now, claim more later” can add tens of thousands of dollars to the lifetime amounts you receive from Social Security. If you start benefits early, however, that option isn’t available to you.

Survivors benefits (for current and former spouses) can be up to 100% of the earner’s Social Security benefit. If the earner hadn’t begun receiving Social Security checks, the survivor’s benefit is based on what the earner would receive at full retirement age. If the earner was receiving Social Security when he or she died, the survivor’s benefit is based on that amount the earner was actually receiving. (This is why it’s often smart for the bigger earner to delay starting Social Security at least until full retirement age, if not longer, especially if the earner’s survivor will depend on that benefit.)

As with other Social Security benefits, applying for survivor benefits before you reach your own full retirement age will result in a reduced check. However, with survivor’s benefits, you can receive a reduced check as early as age 60. (The earliest you can get spousal benefits is 62.) The starting age is even earlier—50—if you are disabled and the disability started before or within 7 years of the worker’s death, or at any age if you take care of the deceased earner’s child who is under age 16 or is disabled and receives benefits on the worker’s record.

Unlike spousal benefits, a late remarriage won’t cut off your checks. If you remarry after you reach age 60 (or age 50 if you’re disabled), that marriage will not affect your eligibility for survivors benefits.

AARP has a primer about how to maximize your Social Security benefits that’s well worth reading. T. Rowe Price has a free calculator to help you determine the best time to take benefits. If you want a more robust tool, check out www.MaximizeMySocialSecurity.com for a $40 version that allows you to play with more