## Working

Australia Day is fixed by legislation to **26 January** each year. When determining whether a substitution applies, I need to check the day of the week.

**Day-of-week calculation for 26 January 2026:**

- 1 January 2026 = Thursday
- 8 January 2026 = Thursday
- 15 January 2026 = Thursday
- 22 January 2026 = Thursday
- 26 January 2026 = **Monday**

Because 26 January 2026 falls on a Monday (a weekday), no substitution is required. All Australian states and territories observe the public holiday on the actual date.

## Answer

**26 January 2026**