What is the average monthly income of someone on benefits
The PIA for someone who became eligible for SSDI in 2013 is the sum (total) of the following: 1  90% of the first $791 of average indexed monthly earnings. 2  32% of the average indexed monthly earnings over $791 through $4,768, and. 3  15% of the average indexed monthly earnings over $4,768.ow much your Social Security disability benefit will be is based on your covered earnings -- the wages that you paid Social Security taxes on -- prior to becoming disabled.