Do the Math Before Leaping on AT&T's $100 Tablet Discount

AT&T killed off its tablet subsidies earlier this year, but the company's resurrecting the program in promotional form just in time for the holidays. If you buy a tablet through the carrier and sign up for a two-year data contract at the same time, AT&T will shave $100 off the purchase price of the hardware.

The deal stands for any slate AT&T offers, including the new iPad, which drops the promotional price of a 16GB cellular-equipped model to $479. That's less than the price of a starting non-cellular-equipped iPad anywhere else, but do the math and consider your options before you rush out to sign on the bottom line.

The cheapest subscription options entails adding your new tablet to an existing Mobile Share plan for $10 per month, a number that obviously doesn't include any other Mobile Share plan fees. If you're already a subscriber and planned to attach your new tablet to a Mobile Share plan anyway, it makes sense to take advantage of that $100 discount, but note that $10 per month adds up to $240 over two years -- and you'll be subject to early termination fees for the slate if you decide to switch carriers sooner.

The offer seems less enticing if you're not adding your new tablet to a Mobile Share plan. AT&T's tablet "DataConnect" pricing plans stacks up as follows: