T-Mobile is expanding its Data Stash program. The company on Monday announced plans to bring its data rollover feature to prepaid customers on Simple Choice plans.

Starting March 22, all eligible prepaid customers will receive a Starter Stash of 10GB of 4G LTE data. Once this is used up, customers will start rolling forward any unused data from the previous month that'll be good for up to a year. Team magenta says the new feature will be activated automatically at no extra charge.

It's worth pointing out that the additional feature is only applicable to T-Mobile's in-house prepaid service; the offer doesn't extend to MVNOs that happen to use T-Mobile's network such as MetroPCS.

In a blog post announcing the expansion, T-Mobile said that more than 40,000 tweets were published last year from customers asking their wireless carriers to let them keep unused data (an obvious jab at some of its competitors).

Thus far, only AT&T has followed suit with its Data Rollover system. The key difference here, however, is that AT&T only gives its users 30 days to eat through any unused data versus 12 months on T-Mobile.

The disruptive carrier further revealed that 27 percent of its customers that already have Data Stash have dipped into their rollover minutes after just a few months. Clearly, this is a promotion that a lot of people are getting behind. Of course, it's all a moot point if you happen to have an unlimited data package but not everyone is willing to pay that much per month for wireless service.