there was a tax provision many years ago that allowed deferral of gain if a new home was bought within 24 months of the sale of the old one for at least the amount of the gain. the catch was that your tax basis for that new home had to be reduced for the gain that wasn't taxed. so if you did this your basis in the home you just sold (assuming this is the replacement property) is what you paid + improvements since the purchase reduced by that deferred gain. the difference between the sale price of the current house and its tax basis is your current gain. if you meet the rules for ownership and occupancy you can use the current rules for home sale exclusion.
