This is applicable for the following models:
Surface 2
Surface Pro
Surface Pro 2
Surface 2 with LTE on AT&T
Refurbished models
Valid 3/23/2014 until 3/29/2014, or while supplies last. Not valid on prior orders or purchases; cannot be transferred or otherwise redeemed for cash or gift cards. Not combinable with other offers. Price discount does not include taxes, shipping or other fees. Void where prohibited or restricted by law. Microsoft reserves the right to modify or discontinue offers at any time. Limit 5 per customer.
Also here
mceworld 