payment of tax and how to claim back the overpaid tax after selling of the property

I am an overseas non resident property owner. I owned a letting apartment and used an online tax filing software to file the tax return for 2023-2024. According to the calculation listed in SA110, the amount of tax I need to pay is £1744.60.This is the first time I need to pay a tax over £1000 arising from the rental received from my letting apartment. To my understanding, I have to make 2 payments on account. The first payment is £2616.90 due on 31.1.2025. the second payment is £872.30 due on 31.7.2025. My question is as follows: (1) the total payment as listed in SA110 is £2626.90 + £872.3 =£3499.20. This £3499.20 doubled my tax payable £1744.60. Isn't this calculation correct? If yes, then I need to pay double tax amount to cover the estimated tax payable £1744.60 for the period of 6.4.2024 - 5.4.2025 . (2) I am thinking to sell the apartment. If I could successfully sell out the apartment in 2024 (after 5.4.2024), say in Sept 2024, as I have paid the whole 2024 -2025 tax £1744.60, how can I claim back the surplus that I have overpaid to HMRC? Please note that I have no British bank account and I made the tax payment to HMRC vide my expat bank account. How can the HMRC refund the money to me? (3) After selling my apartment say in Sept 2024, do I need to file the tax return for the period 2024 - 2025 and the years thereafter? Can I close or cancel my HMRC tax account? If yes, by what means can I make it? [Hope you would understand that it cost money to file the tax return in the HMRC recognized tax software and it is a very complicated work for me to file the tax return every year. ] Many thanks for your help and advice in advance.

Hi,

Your liability for 2023 to 2024 was £1744.60. Payments on account (POAs) were set at half of this £872.30, so the payment due at 31 Jan 2-25 would be £1744.60 + 872.30 (£2626.90) and 31 July 2024 £872.30. In this way you have paid £872.30+872.30 = £1744.60 for 2024 to 2025 in advance of the end of the tax year.  
The POAs are initially set at half of the previous tax years liability. They can go up or down as your circumstances change and ideally, will collect all of the tax due.
If you dispose of the property during the year, then your income will be less, and your payments on account will reduce. You will need to work this out yourself.  
Please have a look at the guidance on payments on account below, which will explain how payments on account arise.

Understand your Self Assessment tax bill

If you dispose of the property, as a non UK resident, you will need to declare the disposal within 60 days of the completion date.
As you can submit your tax return online, you can use your government gateway user ID and password to report and pay any capital gains tax payable at:

Tax when you sell property

There is also a calulator there to help work out if a gain arises.
If you no longer meet the critieria for completing a self assessment tax return, you should notify HMRC, so that your self assessment record can be closed.

Thank you.

Many thanks for your advice at first. I have read the link of capital gains tax, However, I am not sure about how to fill in the 'value when you sold the property'. Unlike the item of 'value when you bought the property' in which it is clearly stated that I just need to fill in the respective share of the property that I own, the 'value when you sold the property' does not specify if I should put in the share amount that I own. I own the property under joint-tenant ownership, hence I only got 50% share. Should I fill in the half value of my sold property or the full value? Say, if the property is sold at £700,000, then should I fill in £350,000 or £700,000? I suppose it should be £350,000 not £700,000. Please advise. One more question please, I think my second payment of £872.30 should fall on 31 July 2025, but not 31 July2024 as stated in the first paragraph of your above advice, since by 31 July 2024 the deadline for submission of tax return has not yet due, hence I should not be charged for the tax amount that has not been reported. Many thanks for your advice again!