If you're a T-Mobile subscriber, the wireless carrier wants to say thank you by giving you one free share of its stock. If you convince a friend to sign up, you get even more stock. But before you decide to accept the largesse you should know that the gift has a few strings, courtesy of your friends at the U.S. Internal Revenue Service.\nIf you sell your stock, you'll be taxed \u2014\u00a0how much depends on your normal tax rate and the share price \u2014\u00a0and you'll need to fill out additional tax forms. If you get more than one share, you'll be taxed, even if you don't sell it. So is it a bad deal? Not at all. It's simply the modern day equivalent of getting a toaster when you opened up a savings account in old days. However, the IRS didn't tax those toasters.\nT-Mobile's other thank you gift \u2014\u00a0free stuff every Tuesday \u2014\u00a0got off to a bad start, after numerous reports of app crashes prompted the carrier to pin the blame on heavy demand, via Twitter.\nFree T-Mobile stock comes at a price\nAs part of the latest installment of its "Uncarrier" marketing campaign, T-Mobile is giving away the stock to members of its reward program.\u00a0All subscribers who agree to accept to the terms are granted one share of T-Mobile common stock. Subscribers who subsequently succeed in getting someone to open a new T-Mobile account will be rewarded an additional share per referral, up to 100 shares a year.\nThat first share is treated as a rebate on the customer's bill, and it isn't considered income until it's sold. However, subsequent shares must to be reported as "other income" to the IRS, according to Denis Maurer, a San Francisco tax accountant. That means the value of the unsold stock is treated just like any other income, and it is taxed at the same rate. "T-Mobile wants to expense the gift, so it has to be treated (by the recipient) as income." Maurer says.\nIf you decide to sell the stock, it gets more complicated, because the IRS treats stock sales differently than other forms of income. Generally, any gain on the sale is taxed as a capital gain. The gain is the difference between the price it was purchased at and the sale price. Though T-Mobile customer won't actually pay for the stock, its value is the share price on the day it was transferred to them, according to Jeffrey Kaufman, a CPA based in Daly City, Calif. If you receive more than $600 in stock in any year, you need to file a W9 form with the IRS, he says.\nCapital gain tax rates vary according to the tax payer's overall tax rate and the length of time they hold the stock before its sale. If it's sold it in less than 366 days, its owner pays a much higher rate than if they wait a year and a day. For what it's worth, T-Mobile shares were priced at $43.74 on Tuesday, so customers are not likely to make significant money on the deal unless they refer a lot of friends.\u00a0Customers must also open brokerage accounts to hold the shares, but T-Mobile will provide free accounts at its brokerage partner, LOYAL3.\nT-Mobile's other thank you gifts are less complicated and not likely to cause tax headaches. For example, customers can carry out one free medium two-topping Domino's pizza, a free small Wendy's Frosty and a free movie rental from VUDU, Walmart's video on-demand service. The company says it will also give away more gifts every Tuesday.\nTo get any of these goodies, customers must download T-Mobile new "Tuesday" app, but the company's servers were apparently overwhelmed on the first day of the promotion. T-Mobile promised to get them up and running as soon as possible.