The Simple Truth
If you served in the military and have a service-connected disability, the VA pays you disability compensation based on your rating (10% to 100%). If you also paid Social Security taxes during your working years and can't work due to a medical condition, Social Security pays you SSDI. These are independent systems with different rules, and they don't interfere with each other.
The VA asks: "Was your condition caused or worsened by military service?"
Social Security asks: "Can you work?"
These are different questions, so you can qualify for both.
β No Offset, No Reduction
Your VA disability check does not reduce your SSDI check. Your SSDI check does not reduce your VA disability check. You get both in full. Apply for both.
Common Misconception: VA Rating = SSDI Approval
A VA disability rating does not automatically qualify you for SSDI, and vice versa. You might have a 30% VA rating and not qualify for SSDI (because you can still work). Or you might be approved for SSDI but have a low VA rating (because your disability isn't service-connected).
However, a 100% VA rating or TDIU (Total Disability based on Individual Unemployability) is strong evidence for an SSDI claim. If the VA says you can't work, Social Security takes that seriously β though they still do their own evaluation.
π‘ Military Service Credits
Your active-duty military service counts toward Social Security. The military paid Social Security taxes on your behalf, and you may receive additional wage credits of up to $1,200/year for service between 1957 and 2001. These credits can increase your SSDI benefit amount.