T-Mobile’s new billing rule hits credit card users where it hurts — their discount

T-Mobile sign outside of store.

What you need to know

• As of October 24, you can no longer get T-Mobile's $5-per-line discount while using a credit card for the actual payment.
• The carrier tightened its billing logic so the discount only applies when the actual payment comes from a debit card or bank account.
• T-Mobile will notify affected users via text message when their discount is removed for the upcoming billing period.