I don't think it's an actual voucher, you have to ring up. Confusingly there is an email that comes out but it ends up dishing out a Silver. And yes you can defer its use until you are ready. However in your case giving it to the kid may be a good idea, since (a) they softland to Silver too, and (b) if the recipient is new to status they get effectively up to 2 years at Gold (in other words, similar to someone who has made Gold rapidly the traditional or BMI way). It relates to their year, not your year.

Not sure if that works for someone who is actually Silver at the time, though I think it does - and there's no point asking since I doubt anyone in BAEC will know this detail. However it would be good if someone here who gave a Gold Partner card to a Silver at the start of the SCH's membership year could confirm my suspicion that they thereby got 2 years of Gold, per their card expiration date.

So think ahead a bit!