Yes, you can collect on your ex's Social Security

Provided you meet certain criteria, you may be eligible for a bigger monthly payment, courtesy of your former spouse. Given that about 43 percent of unmarried older Americans rely on this government benefit for at least 90 percent of their income, this little bump can be huge, as long as you know about it.

"Divorced benefits and qualifications aren't discussed anywhere on the statement you get in the mail," said Rob Kron, head of investment and retirement education for the asset management firm BlackRock.

"People just don't know they are eligible for this money and often times it goes unclaimed."

See if you qualify

What hurdles do you need to clear in order to collect on an ex-spouse's work record? As long as your ex is entitled to Social Security, you must meet four main criteria:

• Your former marriage lasted at least 10 years.
• You are age 62 or older.
• You are currently unmarried.
• The benefit you are entitled to receive based on your own work is less than your ex-spouse's benefit.

If all that is true, you may be entitled to up to one-half of your ex's full retirement benefit, regardless of when they decide to take Social Security or if they remarry.

Timing is everything

You may start receiving your ex's Social Security as early as age 62 but doing so will permanently lower your benefits because you're not waiting until your full retirement age, which for most current retirees is age 66, to claim.

For example, if you were born in 1955 and file at 62 for your ex-spouse's benefit, you will see a 30 percent reduction in your check than if you waited until your full retirement age.

While the government will penalize you for taking your ex's benefit early, it won't reward you for delaying.

If you were using your own work record, each year you delay filing for Social Security beyond your full retirement age boosts your payment by 8 percent.

That's not the case for ex-spouses.

"It is important to file and commence benefits immediately upon reaching full retirement age because there is no delayed retirement credit eligibility for an ex-spouse," said Chris Ure, managing director at HighTower Boca Raton.

How to figure out which is more

Luckily you don't need to pick up the phone and ask your ex how much their payments will be. Instead, you should be able to compare both payments yourself by making a stop at your local Social Security office or going online to the agency's website. You'll need your marriage certificate and divorce decree before starting the process.

What if you get remarried?