I've left job but owe money apparently

[steeringthewheeloflife]

I left my PT job 2 weeks ago. I left on the day everyone got paid so I had assumed that the pay would have been run for my last actual week, therefore I thought I would get a few quid at the end of this month. I've just checked my HMrC app and it's showin -£80

So I now owe them money. Our holiday year ends in dec so maybe I owe holiday pay.

Is it the same dates as your usual pay cycle?

Yes , had I still been there it would have been 31 st dec. that's also what's showing on my HMRC app

I was half hoping I was getting a few quid so to learn that I owe money is rubbish