| Special to USA TODAYUncle Sam presently pays on average $2,224 per month in Social Security disability insurance benefits to about 8.3 million Americans.And if, for whatever reason, you need to apply for Social Security disability insurance (SSDI), there are a few things you need to know.It’s hard to getFor starters, it’s “very” hard to get, says 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 under Social Security rules 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,” said Landis.Do you have a work history? What’s more, you have to have at least a part-time work history to get SSDI, said Landis.In general, to get disability benefits, you must meet two different earnings tests, according to the 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 retirementMore: How to navigate Social Security when there’s a big age gap between you and your spouseThere are, however, 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 added.And if you’re low-income, you should check out the Supplemental Security Income (SSI) program, provides monthly payments to adults and children with a disability or blindness and who have income and resources below specified amounts.It can take years to process a claimLandis also notes that it could take a year to process your claim. How does the Social Security decide if you are disabled? Well, if you have enough work to qualify for disability benefits, Social Security use 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 you are working in 2021 and 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 opportunitiesFor his part, 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, where PIA is his benefit amount if he began benefits at his FRA. If he becomes disabled at age 64 then he could receive $2,000 per month in benefits even though he is applying for benefits before his FRA, said Reichenstein.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 noted. “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, of course, apply, said Reichenstein.It sometimes pays for a disabled person to suspend retirement benefits at his FRA, as well.Consider, for instance, this case: A disabled husband is age 63½ with a PIA of $2,000. His spouse is also 63½ 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,” said Reichenstein. “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 firstname.lastname@example.org. The views and opinions expressed in this column are the author’s and do not necessarily reflect those of USA TODAY.