John Komolafe

I just start a new job this month, my old job is now a par-time job and my new job is my permanent job, will HMRC decide which is permanent job and which is part time job. Also my first salary in my new job with that of my par time job is about £4500. Will HMRC use this pay to calculate my tax or my tax will be based on my salary at the HMRC calendar year in April.