It's supposed to be every 4 years \ 60,000 miles.
Mine is due in October. I'm only on 30,000 and can't help but think when teu change it the old one will be in perfect condition.
I really think its a bit of a scam and a cam belt done at 5 years is perfectly same.
I think Audi actually state 5 years so what's that saying about VW.