Short answer: QDWI pays only the Part A premium for people under 65 with a disability who lost premium-free Part A because they went back to work. Unlike QMB, SLMB and QI, it is not one of the programs that makes someone automatically eligible for Extra Help.
Medicare.gov: the Qualified Disabled and Working Individual (QDWI) program is for someone who has a disability, is working, and lost Social Security disability benefits and premium-free Part A because they returned to work. It helps pay the Part A premium only. 2026 limits: income $5,405 per month individual or $7,299 couple; resources $4,000 individual or $6,000 couple. The Texas handbook adds that the person must be under 65 and not receiving Medicaid.
Extra Help: 42 CFR 423.773(c)(1) deems people eligible for the full subsidy if they are full-benefit duals, SSI recipients, or eligible for QMB, SLMB or QI. QDWI is not on that list, so a QDWI person who needs drug help has to apply for Extra Help separately and meet its income and resource tests.