prepaid plan

i have jatpack. I have a prepaid plan and pay $35 with $5 autopay discount. I do not pay any other taxes, fees, anything. every month my credit card is charged $35. that's it. I like it. I was wondering if the same applies to prepaid PHONE plans. I want to switch from tmobile. I am looking at $45 prepaid plan 15GB data. I will buy my unlocked galaxy S10 off amazon. does someone have prepaid plan ? do u see any taxes fees etc when your credit card is charged ?