Personal Tax Allowance Reduction

I earn just over £53k which is made up of a salary of £30k & a pension of £23k. My tax code has just arrived and its dropped from an allowance of £12570 to £192. £3337 of that is to reclaim £600 in tax I owe from a previous year (no idea how I end up owing tax on PAYE??), but I have no idea how the other £9000+ is justified. The letter states it's for 'adjustment to rate bands', but I have no idea what that means. I thought you lost your personal allowance over £100k but mines gone now... is this right and if so how????

Hi,

You would need to contact our Income Tax team so we can review your tax code.

Income Tax: general enquiries

Thank you.