The way it works is that she pays for the bike out of her gross salary before tax is deducted. So in short, if she receives €400 nett per week and the bike costs €500 and she wants to spread payment over 6 months (25 weeks), she would have €20 per week deducted from her pay each week before tax is calculated. So lets say her gross is €500 per week and €100 is deducted in tax each week (this is not accurate but just to give an indicative idea). Instead now she would have tax calculated on €480 so her nett take home might be more like €390 per week.