Uncle Sam pays on average $2,224 per month in Social Security disability insurance benefits to about 8.3 million Americans.

If, for whatever reason, you need to apply for SSDI, there are a few things you need to know.

It's hard to get

For starters, it’s “very” hard to get, said Andy Landis, author of "Social Security: The Inside Story."

“Social Security has a very strict definition of disability,” he said.

Social Security considers you disabled if all of the following are true:

• You cannot do work that you did before because of your medical condition.

• You cannot adjust to other work because of your medical condition.

• Your disability has lasted or is expected to last for at least one year or to result in death.

“Basically, you have to be almost totally disabled for an extended time period,” Landis said.

You have to have at least a part-time work history to get SSDI, Landis said.

In general, to get disability benefits, you must meet two different earnings tests, according to Social Security: a recent work test, based on your age at the time you became disabled, and a duration of work test to show that you worked long enough under Social Security.

Don't believe everything you hear: 3 Social Security myths that could ruin your retirement

More: How to navigate Social Security when there's a big age gap between you and your spouse

There are backups if you don't have the work history or if your SSDI payment is low.

“Backups are available for disabled widows and widowers and for disabled adult children,” Landis said.

If you're low-income, you should check out the Supplemental Security Income (SSI) program, which provides monthly payments to adults and children with a disability or blindness and who have income and resources below specified amounts.

It can take a year to process a claim

Landis noted that it could take a year to process your claim. If you have enough work to qualify for disability benefits, Social Security uses a step-by-step process involving five questions to determine if you are disabled.

The list of questions starts with whether you are working. If your earnings average more than $1,310 a month, you generally cannot be considered disabled. If you are not working, Social Security will send your application to the Disability Determination Services office that will make the decision about your medical condition.

Planning opportunities

William Reichenstein, co-author of "Social Security Strategies: How to Optimize Retirement Benefits," said there are some little-known financial planning opportunities for those collecting SSDI.

Consider, for instance, a man with a full retirement age (FRA) for retirement and spousal benefits of 67 and a primary insurance amount (PIA) of $2,000, in which PIA is his benefit amount if he began benefits at his FRA. If he becomes disabled at age 64, he could receive $2,000 per month in benefits even though he is applying for benefits before his FRA, Reichenstein said.

Social Security misinformation: Here are 3 stats that could spell trouble for retirees

“At his FRA, his disability benefit automatically becomes his retirement benefit with the benefit amount remaining constant,” he said. “If he is married and receiving disability benefits, then he can also receive spousal benefits based on his wife’s record, or his wife can file for spousal benefits based on his PIA.”

The normal rules governing spousal benefits would apply, Reichenstein said.

It sometimes pays for a person with disabilities to suspend retirement benefits at his FRA, as well.

Consider this case: A disabled husband is age 63? with a PIA of $2,000. His spouse is also 63? with a PIA of $700. They both have an FRA of 66 years and six months. He can begin disability benefits of $2,000 per month. She could begin her retirement benefits of $560 per month, plus spousal benefits of $225 per month, for total benefits of $785.

At FRA, he could suspend his retirement benefits. His wife would lose her spousal benefits, but she could continue her retirement benefits of $560. At 70, he could start his retirement benefits of $2,480 per month, which reflects three years of delayed retirement credits, and she could add spousal benefits.

“The benefit of him suspending benefits at FRA is that, after his death, his wife would continue his benefits of $2,480 per month,” Reichenstein said. “In contrast, if he does not suspend his benefits, then her survivor benefits would be $2,000 per month.”

Robert Powell, CFP, is the editor of TheStreet’s Retirement Daily and contributes regularly to USA TODAY. Got questions about money? Email Bob at [email protected].

The views and opinions expressed in this column are the author's and do not necessarily reflect those of USA TODAY.

This article originally appeared on USA TODAY: Boost your Social Security benefits if you’re collecting disability insurance