This is a response posted to a similar query last year. Its from MOB:
" Unless special arrangement is made, you are entitled to interest at the demand deposit rate applicable to your money in the solicitor's bank -as the money held by the solicitor is available on demand. The solicitor may well get a better rate, but that is because your money is held with lots of other money - which is the solicitor's good fortune, not the client's.
I think the demand rate right now is less than 0.4%. So, let's say €300k purchase money @0.4% = €1200 p.a. (before DIRT) or €23 for the week. And, as Vanilla says, there is no requirement to account for sums of less than €100 (actually it might even be €150).
In this example I have assumed a demand deposit rate of 0.4%. For smaller sums, you could be talking as little as 0.1% right now."
mf