Under the new Itis system, the onus is on taxpayers both to calculate whether they have overpaid and then to take steps to recover the money if they want a refund.
David Le Cuirot, the acting deputy Comptroller, accepted that more information could have been provided about rebates.
However, he said that most people kept a track of how much they had paid and how much they were liable to pay, and it was up to them to inquire about any refund.
He added that anyone who had already paid his or her tax bill for 2005 could contact the department and claim back the money immediately.
Those people would be given a zero return for the rest of the year.
It is expected that repayments will take two weeks to be paid out.
Alternatively, the overpayment can be carried over as a credit for next year, meaning that people will pay less tax during 2007.
