How Long Should I Live in a Property for it to Become My Main Residence?

Question My partner, who has lived with me for the last two years, has a property that he lived in for 3 years, before moving in with me. He is letting out his property but at some point we will want to buy together and sell both properties. My understanding was that you only needed to live in a property you have let out for 6 months at some point to not be taxed, but are you saying there is some rule regarding letting it for more or less than 3 years or living in it for more or less than 3 years?
 
My situation is that I have had four buy to let properties for a few years now. I will sell them off one by one eventually. The only way I can avoid tax is by living in them for 6 months or more before I sell them, though you did say somewhere else the tax people are cracking down on that?

Arthur Weller Replies:
There is no official minimum time that a taxpayer needs to be living in a property to make it qualify as their principal private residence (PPR). It is dependent on the 'quality of residence', i.e. the taxpayer needs to show that they moved in and resided with a 'degree of permanence, continuity or the expectation of continuity'.

Some tax advisers would advise six to twelve months of full occupation but other people would advise different amounts. See the Capital Gains Manual page CG64420 on the HM Revenue and Customs website: http://www.hmrc.gov.uk/manuals/cgmanual/CG64420.htm