SSDI is increased each year according to the Cost of Living Adjustment (COLA) for that year.
Social Security law states that benefits will increase automatically each year if there is an increase in inflation. (In general, the COLA is equal to the increase in the Consumer Price Index. If there is no increase in the Consumer Price Index, then there is no adjustment in benefits that year).
On the other hand, Social Security benefits cannot be reduced even if there is deflation. Deflation is a decrease in consumer prices that drives inflation below zero.
For the current COLA information, visit SSA’s Website.