Selling main residence and move to my rental

[kevo567]

I want to one day buy a bungalow in a nice area, to do this we would need to sell our main home and our rental, however we do not want to do this for a few years yet and selling the rental now could be complicated as it was left to me and my sister, and I bought out her share 4 years ago.
Therefore we are planning to sell our main residence and move to our jointly owned rental and make this our main residence for at least 2 years, before selling it, and then using the proceeds of both sales to buy a nice bungalow.
I am wondering if we will have to pay CGT on our former rental after living in it for 2 years. We are both retired and are lower tax rate payers.
Any advice / ideas will be more than welcome.

[pawncob]

The rental will qualify as your PPR while you occupy it, and the gain on sale will be time apportioned to determine the chargeable amount.
You'll also get Letting Relief, so the gain may not be too bad.

[kevo567]

Thanks pawncob, I think I now need to provide the full history of our family home, sorry but its complicated.
1982 bought from council, value was £14,300 less discount leaving a mortgage of £7500, my mother / father and sister were on the land reg. sister did not contribute to the mortgage payments and was on the mortgage so they could get it using 3 wages.
1998 sister got married and moved out, house was officially signed over to me and my sister (both of us on land registry) but mam and dad remained in the house until their deaths in 2010 and 2013 . Value of house in 1998 is estimated at £30k.
2013 (July) We had the house valued (£79k) and I agreed to buy her share (£39500) and became the sole owner, I spent £12K refurbishing it then letting it in April 2014.
2015 added my wife to the land registry (50/50), the letting will end in April 2020 when we plan to move in and make it our permanent home for a few years.
I don't believe there was any IHT to pay but can see there will be some CGT to pay once it is sold and would appreciate some idea of who will have to pay it, will my sister have to pay anything?, should she have paid something in July 2013? Maybe I should just sell it and forget about moving in for a few years. Like I said, its complicated .
My thanks in advance for any help / suggestions.

[pawncob]

Any gain will be based on purchase price (not stated).
The question is, did any of these people actually contribute to the purchase?
Assuming you all had quarter shares, sister sold her half share for £39.5k. Cost was 25% of purchase price plus 50% of probate for each parent. She should have declared gain on sale.
Your cost is 25% of purchase plus 50% of each parent plus £39.5k. This figure (half) will also apply to your wife.
Both siblings may be entitled to PPR for period when they occupied, and you may have further PPR if you re-occupy, as well as Letting Relief.