Amidst the hullabaloo with T-Mobile raising its plan prices, the Un-carrier quietly stopped including taxes in the prices of its Business Unlimited plans. According to PhoneArena, the change was implemented in May but people are only realizing it now. 

Before the change was made, T-Mobile included taxes and fees in the price of its business plans for those with less than six lines. But now, users have to pay taxes on top of their monthly plan rate. 

Since this only affects Business Unlimited plans, it will not affect regular users. It also only affects new customers. Existing customers will continue to follow the same pricing. 

Source: PhoneArena