Say you buy the house in Jan 2000 for €200k and use it as your PPR until Dec 2002 (3 years).
Then you rent it from Jan 2003 until Dec 2005 using another dwelling as your PPR (3 years).
The house value in this time rises from €200k to €400k.
My understaning is as follows (this is a very simplisitic/rough understanding):
You own the house for 6 years.
3 years as PPR, 3 years rented.
The house value rises be €200k.
50% of the time is rented (not PPR) therefore you owe CGT at 20% on €100k = €20k.
I think there is a clause stating that if you sell the house within 12 months of it ceasing to be your PPR you don't have to pay CGT.
I can be corrected on this however.
Don't take this as gospel.
If you do some searching on this site I'm sure you will find this is covered in more detail.
