Paye employed in the 40% tax bracket + freelance all going into my sipp

Hi wondering if anyone can shed some light on my confusion as I’m attempting this for the first time. I’ve got to the end of my tax assessment 23/24 and I’m at the tax calculation part and I’m a bit confused. - Basically I’m a 40% tax payer in full time work. I made 58772 last year - I do freelance on the side and made 15910 - I put all my freelance profit into my sipp, 15910 where I got 20% relief at source So I had to do a tax assessment to claim additional tax relief on the 15910. I’ve got to the end of my tax assessment and it says - I owe £3690.79 2023-24 balancing payment - 1st payment on account for 2024-25 due 31s Jan 2025 is 1800.50 - total to be added to self assessment account due by 31 January 2025 is £5491.20 Second payment on account for 2024-25 will be due by 31 July 2025 That’s a lot of tax I wasn’t expecting? I’ve already been taxed on my full time job. So was expecting no tax there Then all the profit I made from freelance I put into a sipp, so there so by no tax there too? Can anyone help?

Hi Amy R,
You are due to pay tax on your freelance profit at 40%, but as you paid this into your pension scheme, you can claim 20% tax relief on this pension payment.
This reduced the unpaid tax to £3690.79.
In addition to this you have met two criteria, that result in payments on account being created.
These are two payments you make in advance of the end of the tax year.
So just as your employer deducts tax monthly from your salary in advance of the end of the tax year.
HMRC are doing the same with your freelance profits.
Ideally, those two payments on account should pay all of the tax due on your freelance work.
Please have a look at the guidance on payments on account here:
Understand your Self Assessment tax bill
Thank you. 

 

Hi am I due ni? with this? I can't get the math right for £3690.79 either. Do you have a formula for it? I understand the last two numbers now as advanced payments. ty!

Hi Amy R,
You will be liable to class 4 National Insurance on your self employed earnings if they are over the limit. there is no formula.
Thank you.

There must be a formula to get to that number? The £3690.79 I cant seem to work out how it came to this. I read some things since. Seems I could have put 80% of what i made into the Sipp and you top up then with the money left over i pay back the 20% you gave me? Is that correct? Also I have a full time job this was a one off job i was paid the £15910. Do i need to register as a business for one off work?