You can now claim refunds for season tickets as well on the Müpa Budapest website

In the event that you feel ill, notice flu-like symptoms or suspect you may have been infected with the virus, please do not visit Müpa Budapest. Instead, in order to recover as quickly as possible, please stay at home and give your ticket or season ticket to someone else. 

If it is not possible to do so, or if you prefer not to go out in public, or in the event that the performance was cancelled, you can return your individually purchased tickets and also tickets for cancelled seaon ticket performances anytime up until the day of performance (or in the case of cancelled performances, up until 30 days after the scheduled date).