If you earn over the reasonable living expenses for your circumstances then you are liable to pay the excess over 5 years. This 5 years can start at any time during your bankruptcy, it's in your interest to get it started as early as possible if it's inevitable.
In your case, assuming you have no special costs, the allowance per month would be €933.14 + reasonable housing costs.
In theory, everything over this is liable to be used in an Income Payment Agreement (IPA). I don't know in practice if there is a percentage one can exceed the amount by before an IPA is sought or whether the IPA will involve taking 100% of the excess.
It's worth noting that these allowances are more generous than the UK.
More info here: [broken link removed]