Lausanne tourist tax is CHF 5.00 (1-star), CHF 5.50 (2-star), CHF 5.50 (3-star), CHF 6.00 (4-star), or CHF 7.00 (5-star) per person per night. It is capped at 90 nights. The requested highest standard adult rate is CHF 7.00 per person per night.
The page states that the tax applies to visitors aged 12 and over; therefore, visitors under 12 are exempt according to the stated age threshold. No reduced rate is stated.
Confirm current registration rules with the city of Lausanne