Your daughter should complete a P46 immediately. Her employers should have requested one when she started her employment, or before her first pay day, in order for HMRC to issue her with a correct tax coding, otherwise they could also suffer a financial penalty.
Your daughter's employers are probably using the emergency code BR, which means that she is paying 20% on all her earnings, without any allowances being given. If she started work and was paid in the last tax year, she needs to get in touch with HMRC to claim a rebate.