The annual return in GSTR-9 consolidates the year’s outward supplies, tax paid, and credit availed. Assessees above the notified threshold also file GSTR-9C, which reconciles the books with the returns. Differences that were left open in monthly filings surface here and have to be explained or paid.
Work starts from the trial balance and the twelve GSTR-3Bs, not from a blank form. Tables are filled so that the annual picture can be defended if the department later opens an assessment.