each and every deposit account has to show the interest paid and the dirt deducted at a minimum of once a year or on account closing.
Some pay quarterly so its posted on the statement each quarter.
get the relevant statements, either paper or online and do the math, its not hard.
I don't know what the rules were but is just time and capital apportionment so as you are only claiming for the correct period with the correct amount:
eg u had 200k on deposit but only 100 went to house, so 100/200 of the interest is relevant.
suppose the relevant interest was 660 euro and the deposit was for 3 years but only 2 years was allowed, then 440 is the relevant, time apportioned interest.