First Year Self Assessment, Employed & Self Employed

Hi, This is my first year of doing a self assessment tax return. I am currently employed and self employed too. During the tax year of 2023-2024 I was employed from April 23-Jan 24 and then changed jobs starting from Jan 24 - April 24. When putting in figures from P45/P60 do I calculate them pro rata or will the system do that for me? Secondly, with the "View Your Calculations" - how do payment on accounts work? How can the tax for the next year be calculated without knowing what the income is? The payment on accounts in addition to the tax bill from the previous year mean that I am paying over the entire income in tax and as a result not having any earnings. Please can this be explained?

Hi,
The P45/P60 will show the pay and tax details for the the tax year so you would enter the details as shown you do not need to pro rata. The payments on account for the 2024 to 2025 tax year are based on your 2023 to 2024 tax calculation.
If the balance due is greater than £1000 and less than 80% of the tax deucted at source then payments on account are due. Details online at:
Understand your Self Assessment tax bill
Thank you.