Maximum relief for FTB married is interest paid or limit whichever is lower.
2008 - max of €20,000 at 20%
2007 - max of €16,000 at 20%
2006 - max of € 8,000 at 20%.
2005 - max of € 8,000 at 20%.
Sorry just noticed you said you were out of FTB in 2004 so the rates for non-FTB are as follows:-
For non-FTB married is interest paid or limit whichever is lower
2008 - max of € 6,000 at 20% you most likely paid > so its €6,000 at 20%
2007 - max of € 6,000 at 20% you most likely paid > so its €6,000 at 20%
2006 - max of € 5,080 at 20%. you paid €18,000 so its €5,080 at 20%
2005 - max of € 5,080 at 20%. you paid € 9,000 so its €5,080 at 20%
Still looking at over €4,000 TRS refund claim though. Enough for a nice holiday or, in current climate, a 2007 BMW