Anything over €15k will be at the lower rate.
To avail of the higher rate you could deposit €14,500 as suggested or else you can manually move your interest earned into another account to keep the lump sum under €15,000.
Hope this helps.
In fairness, 4.33% is almost as good as anyone else is offering for instant access, since Rabo's recent announcement.the entire 15,005 at low rate![]()