Payroll calculations stop
This is the sharp edge and the reason the date is not negotiable. After retirement there are no further payroll calculations and no compliance updates. Sage has said the last payroll update lands in July 2026, with a year-end update in November or December 2026 for T4 and T5018. Run a pay period into 2027 on BusinessVision and you are calculating source deductions with rates nobody is maintaining.