Straight line, Rebasing or Gain over whole period method, which is it, please help!

We lived in our UK family house for 7 years from 2004 before moving abroad in 2008 and have been renting it out long term ever since. We now want to sell the house but buy a small apartment. We have tried imputing the details several times into the CG calculator on GOV.UK but really struggling to understand which of the three tick box choices we would have to choose as there is a big difference in cost, we would like to know roughly how much we would need to pay before selling. Please help! 1)Straight line apportionment method , 2)Rebasing 3) Gain over whole period of ownership method

Hi Michaela Robinson,
It is up to you which method you choose.
The rebasing method can apply as you owned the property prior to 2019 and its the market value at that date rather then 2004.
This may be more beneficial.
More guidance is at:
Work out your tax if you're a non-resident selling UK property or land
Thank you.