There are two different types of disability benefits: SSDI and SSI. This post will focus on SSDI (Social Security Disability Insurance) and how you can obtain this coverage.
When you work and pay your taxes, one of the items subtracted out of your paycheck is FICA (Federal Income Contributions Act). Your FICA contribution pays for Social Security and Medicare. (For 2019 it is 7.65%). Your employer will pay a tax equal to the amount withheld from your paycheck. Thus, you pay half of your FICA tax, and your employer pays the other half. If you are self-employed, you will have to pay both halves of that tax. (For 2019, it is 15.30%). So, if you are only working cash jobs, or not paying taxes, then you are not paying FICA, and you are not earning quarters of coverage.
Assuming though, that you are working and paying into FICA, then you are earnings quarters of insurance coverage. SSDI is an insurance program purchased through the Federal Government that provides benefits if you are no longer able to work. In many ways, it is similar to a Long Term Disability policy you might pay for through your employer. Whether you have coverage will depend on your quarters of coverage.
Quarters of Coverage. Each fiscal year is divided into four quarters, so at most, you can earn four quarters of coverage each year. The administration sets the cost for a quarter of coverage which varies from year to year. For example, in 2017, a quarter of coverage was $1,300. So to earn four quarters, you would need to pay FICA on at least $5,200 of earnings. The cost per quarter per year can be accessed here: https://www.ssa.gov/oact/cola/QC.html
The 20/40 Rule. To be fully covered, you need to have earned 20 quarters of coverage over the last 40 quarters. In other words, you need to have earnings in 5 of the previous ten years.
Those earnings do not have to be in consecutive years, but the stronger your work history, the more likely you will have sufficient coverage. Your insurance can expire. Many people are not aware that their coverage for SSDI can expire. Many incorrectly believe that if they have paid in, that coverage will always be available. However, SSDI is an insurance policy. As with any insurance policy, if you stop paying the premium, then the insurance lapses. For SSDI, if you stop paying FICA, the insurance will lapse. Assuming you were fully paid in at the time you stopped working, then your SSDI insurance will expire in five years. Accordingly, you have five years from when you stopped working to prove that you became disabled.
How much money per month? On SSDI, the amount of money you will receive every month depends on how much you have paid into FICA. The maximum is raised periodically. For 2019, the maximum SSDI payment is $2861, and the national average is around $1,200 per month.
The above is general information about SSDI benefits. If you want specific information about your particular situation, you can create an online account at ssa.gov. You can also visit your local Social Security Office.