Self Assessment - Payments on Account

I complete self-assessment as I have income from UK property. That is my only source of income - I am not employed or self-employed. In the calculation of tax payable for 2022-23 a payment on account for tax year 2023-24 has been included. I have been doing self assessment for a number of years but have never been required to make a payment on account before. I therefore wanted to check that: (a) it is possible that a person who is not self-employed might be required to make such a payment, and (b) the possible reasons why that would be the case? Thanks.

Hi,
Payments on account occur, when two criteria are met.  
There is an self assessment underpayment of tax of more than £1000.00 and less than 80% of the unpaid tax can be collected automatically (such as via a tax code operated by an employer).  
If both criteria are met, then the unpaid tax for the year, is used as a starting point for the next tax year, to create payments on account.  
Payments on account allow you to pay the tax due for the next tax year in January and July, with any shortfall payable as a balancing payment.  
More information can be found at:
Payment of tax: payments on account
Thank you.