work moved to a new pay system and it mucked up everything in terms of expected salary so tax man thought I owed more tax than I would and gave me a code which meant they added £7700 onto expected salary from Dec to end Jan. now work has corrected tax code has changed to giving me a £8800 personal allowance now with 2 months left before the new tax year begins. I assume I’m owed tax back which I hope I’ll get back in next months pay. HMRC app updates a week before I get salary and it says income tax is -£14788 and usual national insurance will be paid. How much am I likely to be refunded? I’m a higher tax payer.