In both your examples it appears you are living in the property as your home, thus it is your PPR and the 18 months will not be deemed PPR as it already is.
But my 1st question was " if owner rents his residential property for 18 months only, " and than returns to property for sometime and than eventually sell the property, would CGT be payable on this scenario ? Basically he is using only 18 months by letting property for only 18 months .
2nd question was " If owner rent his private residency for 4 years or more, and than returns to live in property refurbishes property lightly while living on it and than eventually sell the property. Would last 18 months still counts as his deemed PPR and consider when carrying calculation for CGT bill ?
Why are you renting the property out. If it is due to working away then you may be CGT exempt. You also do not appear to have considered Letting Relief which may wipe out any CG. Regards Peter
Property will be rented as owner will re-locate to other part of UK do to work commitments.
To simplified, in both questions, would you lose last 18 months deemed resident if you return to property ?