Tax Details Not Updated Automatically In Cellular Provider Billing Service Make Money Offline

I spoke to one of my friends this morning. The friend found a new job and he recently moved from Tennessee to New Jersey. He changed his new address in all his billing accounts including energy providers (Jersey Power in New Jersey), cellular billing, landline phone, mailing address, auto insurance, health insurance, home insurance etc.
He checked his cellular bill the next month. It is the first month after moving to New Jersey. He found that there was no change in the amount. He contacted the customer service. They changed his bill and New Jersey state tax took effect.
 
He wished he could have changed it after 1 year (as the new bill was $3 more owing to greater tax percentage...just fun)..
I wanted to share this experience with you all because most of the billing systems don't have provision to take changes into effect automatically. So, kindly check it. If you are moving from say NJ to TN the tax percentage will be less...So, never end up paying more...PENNY SAVED IS PENNY EARNED