The 0% financing gets you on monthly taxes and fees. It's not really 0%, more like $5 per month financing per device. I bought a new phone through T-Mobile which let me get a 10% rebate on it through American Express, but paid it off as soon as I saw the real monthly charges.
So get the $100 off but avoid the financing if possible.
You had me worried, so I had to go back and check. We have a lease and we aren't paying anything more than taxes for the phones. Our total phone cost comes out to $623.99 + taxes, which is for the $749.99 phone. The reduced cost was a $126/phone promotion that is credited to our account each month.
When I read your post, I went and looked at our billing and it's not the easiest to decipher. I ended up calling T-Mobile to make sure I understand all the charges.
There are two parts to the bill. The first is for the overall plan and the second is for each phone. This is where I made a mistake earlier in this post regarding the total cost of our plan. Our plan costs us $93.89/month, but then for each phone we pay $4.18 in taxes and fees. This comes to a total cost of $110.61/month for four phones.
In the billing for each phone, I see a $2.50 tax for the phone, which is 9.6%, our local sales tax rate.
So the numbers add up for the total phone cost and we pay a bit more for the plan each month than I initially thought. But it's still a good deal for four phones with 4GB data per month.
While I was talking with the T-Mobile rep, I asked how much it would cost for four phones with T-Mobile One. We'd have to pay the full $160, no corporate discount (which is 15%). Even with kickback for two phones we'd be paying $140/month. I was also told our 4GB discount is only good until 2/19, at which point it goes back to 2GB/month.
When the new iPhones are released, I'll have to figure out what to do. Maybe we'll put off upgrading for another year? Still plenty of time to decide. Maybe I'll start making DS and DD pitch in.