They must be in date, this is something that has been talked about on here a lot (and im sure Al W will be along soon
)
Over the last few years people have turned up with out of date belts and they will get turned away, after all the money you spend on getting there and entry fees its not worth the risk, at best you will have a very hard time and have to borrow someones belts (and all the stress!!!) at worst you will lose your money.
Although 44 says that they must be fitted in accordance with MSA and FIA instructions, and these instructions include the date.