The regulations about deductions that can be made from an employee's payslip are set out in the Payment of Wages Act, 1991. [broken link removed] sets out the actual rules regarding deductions.
The bottom line is that you are obliged to re-pay the overpayment. As regards the method of re-payment however I might suggest you read through the terms of Section 5 (in particular to parts 3, 4, 5) to see what the law actually specifies.
As far as I know, the salary deductions made to recover the overpayment should be fair and reasonable but again you would need to read through Section 5 to check this exactly.
Staff in the Employment Rights Unit at the Dept. Enterprise, Trade and Employment will be able to answer this question definitively. (Tel: 1890 201 615). By the way, I would not recommend you go into that meeting without checking out all the legal avenues beforehand.
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