Do Xbox Live Gold Subscriptions Stack?

So, I've stacked up some Microsoft Rewards points, and noticed that there's a sale on the cost of a 12-month Xbox Live Gold membership. I'm able to buy it, and gladly would. However, it's only been months since I bought my last 12-month Xbox Live Gold Subscription.
If the two of them stack up if I take up the MS Rewards offer, and I thus have a year and several months left (as a result of the MS Rewards purchase) before I need to purchase my next subscription, then I'll be inclined to consider it. But, if making this
purchase essentially only replaces my subscription (AKA gives me at best 12 months before I require another subscription), then I'm not nearly as inclined to take MS Rewards up on their offer.

What I'd like to know is, which way does it work? Will having these multiple subscriptions at the same time cause them to stack up, or essentially restart my 12-month subscription?

:)

 

1 year Xbox Live Gold - $36

xbox live 12 months gold subscription card gold pl eu us for 33$ (PL/EU/US)
Xbox Live - Buy 12 Months GOLD Subscription Card (Global)

 

1 year Xbox Live Gold - $36

Never heard of either of these places... always a little sketch to do it.

EDIT: Seems it went up to 43$ now.

 

Yes, gold stacks. You can add up to 36 months of gold at a time.