CGT is relevant when one disposes of a capital asset (e.g. property, land, shares). If somebody sells a piece of land then in all likelyhood the sale will be assessable for CGT payable by the seller. In summary CGT is 20% on the disposal price (or market value if the disposal is at a discount) less the acquisition price (indexed for inflation up to 2003 (?) if applicable) less allowable expenses less one's annual CGT exemption of €1,270 if applicable. There may also be other tax implications (e.g. SD on the purchase payable by the buyer). If in doubt get independent, professional advice.