Masters' Students Working Hours and Tax Process

I am currently a master's student and as a result of the confirmation I received from my school and the research I have done, I have the right to work for 20 hours during the academic calendar and 40 hours during the summer holidays. They stated that I have such a right as I am not in the thesis period. I started my first 20-hour part-time job in March and started my second 20-hour part-time job in June, since my school is on summer vacation. I work 20 hours in both jobs and I never exceed 40 hours. Both businesses know that I work two jobs, and my tax code at my first job is 1257L, and at my second job, which I started later, my tax code is BR. However, there is one thing that I'm curious about and want to be sure of because I don't want to have problems with the visa later on. As far as I know, payments are made on monthly working hours. And if in the future I am asked to prove that I do not exceed 20 hours per week during the academic calendar and 40 hours during the holidays, what should I do? Should I get a letter from the workplace or do I have documents that I need to keep just in case? Or should my workplace take action on this? I would be very grateful if you could help me with this topic.

Hi Basak,
If this situation arises you would need to contact the employer and ask them to provide evidence of your working hours.
Thank you.