xbox live subscription card expiration?

[wiisg]

I plan on buying my brother a xbox live subscription card for Christmas.

Do those cards expire? My concern is that I buy him a card and find out he just renewed since he got the xbox for Christmas last year and the card will sit for a year.

Would it still work?

 

[registerednerd]

I'm pretty sure they don't expire, but I'll check the Ts and Cs on one when I get to work later.