Accompanied or unaccompanied children up to the age of 6 travel free of charge.
Children between the ages of 6 and 16 pay the reduced fare until the day before their 16th birthday. Young people receive monthly and annual travelcards at a reduced fare until the day before their 25th birthday. These can be used until they expire.

With the Junior travelcard (for parents) or Children's Co-travelcard (for other accompanying persons), a child aged 6 to 15.99 year old accompanied by a parent or an accompanying person aged 16 years old or over (grandparents, godparents, older siblings, etc.) travels through Switzerland free of charge for a whole year for CHF 30. The parent/accompanying person requires a valid ticket. A separate Junior travelcard must be purchased for each child and a separate Children's Co-travelcard for each combination of child and accompanying person. The child needs a personal SwissPass to which the Junior travelcard and the Child Co-travelcard(s) are loaded. The Junior and Children's Co-travelcard can be purchased at any staffed ticket counter and at the ZVB counter in the Reisezentrum Zug 

The reduced fare applies to dogs.
Exception: Dogs up to 30 cm shoulder height (instep height), cats and similar tame animals may be carried free of charge in bags, baskets or other suitable containers.
 

Passengers with a disability are authorised to take an accompanying person and/or a guide dog with them free of charge. The traveller with a disability or the accompanying person must have a valid ticket and be able to present the "Identity card for travellers with a disability (accompanying person card)". You can also find more information at SBB.