Social Security's disability benefits program, like its retirement benefits program, has no "means test." If you have qualified for benefits, then you receive those benefits, regardless of how much money you have. So if you're receiving Social Security disability benefits and you inherit money, your inheritance should not have any effect on your benefits.
According to the Social Security Administration, just two factors determine your eligibility for Social Security disability. The amount of your assets is not a factor. The first factor is your work history. Every year that you work and pay Social Security taxes, you earn up to four "credits" toward Social Security benefits. As of 2011, you earned one credit for each $1,120 you received from working, so if you made at least $4,480, you earned your four credits for the year. The minimum number of credits you need to get Social Security disability depends on your age when you become disabled; it ranges from six credits if you're younger than 24, to 40 credits if you're 62 or older.
The second factor in eligibility is the nature of your disability. Social Security considers you disabled only if you can't do the work you were doing before, your disability prevents you from adjusting to new work, and your disability is likely to last at least a year or until your death. One of the factors Social Security looks at in determining whether you are disabled is whether you are earning income. But this applies only to earned income from work. Money from an inheritance doesn't count toward this determination.
Social Security can reduce your disability benefits if you are receiving money from some other public disability benefits program. This includes workers' compensation, temporary disability benefits paid by state programs, civil service disability benefits, and state and local benefits programs that are based on disability. Payments from private sources, such as benefits from a disability insurance policy, have no effect on Social Security disability. And inherited money also cannot reduce your disability benefits.
Though the names are similar, Social Security disability is not the same thing as Supplemental Security Income for the disabled, a separate program administered by the Social Security Administration. The SSI program pays benefits to seniors and disabled people who have little or no income. Because it's based on income, SSI is by definition means-tested, meaning that an inheritance could affect benefits.