Rebasing Method

I'm a non PR, bought a flat in 2011 ( exchanged contract in2011), Due to changes of developers, I signed 2 variation contracts before I got the vacant possession in 2019. Now I intend to sell this flat, shall i use rebasing method which I have to get the flat's valuation as at April 5, 2015 ? If yes, the problems was that in 2015, there was no ready units with vacant possession for this project. In this case, can I use the flat surrounding my project to obtain April 5, 2015 valuation? Or can i use 2019 market value as my flat's acquisition price ? Thanks.

Hi Deric Ng,
If you are non resident in the UK at the time of disposal and you owned the asset before 6 April 2019, the standard approach for working out the gain is to use the market value at 5 April 2019.
Please have a look at the guidance here:
Work out your tax if you're a non-resident selling UK property or land
Thank you.