Zero hours contract - significantly more pay in a month

I have a zero hours contract. If I earn significantly more in a month than I typically earn, could HMRC assume that I am earning over 50k/year and tax me accordingly? Trying to avoid messing up my tax code and keep paying more even if I'm no longer earning the same amount. I don't have to submit all my shifts in the same month, so would it make sense to submit some in one month and add some to the next one (when I know I'll be earning much less)? Also, I'm not sure how it's calculated – if my pay day rate is 180£ (inclusive of holidays), but I always get 157,15£ per day on my payslip before tax (because of holidays), which amount should I use for the 50k calculation? What’s the maximum per month I can earn before being taxed above 50k?

Hi fran_fmrg,
You are taxed on the earnings paid in a given tax period.
As this relates to your individual tax affairs we would suggest contacting personal tax on 0300 200 3300.
More information regarding contacting personal tax can be found at Income Tax: general enquiries.
Thank you.