If I was to make 100K profit on the house in Dublin and not get it sold until after sept 2005 would that mean I pay 20% on the 100K?
I'm not sure how strict Revenue are in terms of enforcing the c. 12 month window of opportunity for disposal of a former PPR before CGT becomes an issue of if that 12 month window is established in law or convention. However, assuming that they are strict about the 12 month window and say you sell the property 13 months later or in week 61 (5 years plus one month) of your ownership then I believe that CGT of 20% will be calculated on 1/61th of the total gain in respect of the month that it was de facto an invetment (albeit non rental) property. Note that the five year timeframe here is not that relevant. You may be thinking about the five year period during which a stamp duty clawback applies if the property originally purchased as an owner occupier is subsequently rented? Please get independent confirmation on this stuff before making any decisions.