There are no minutes, per se, with GoPhone accounts. There are dolar balances. They may be used to purchase air time, features or online purchase such as ringtones, Answertones . etc, If you do not use the funds for anything else, the dollar amount could purchase a certain amount of air time. Remember that dollar balances rollover and not minutes. If you purchase a feature which is not unlimited, your dollar balance would be used to pay for that use once your feature allowance is used up or has expired. So if you purchase a 200 message feature for $4.99, message number 201 would be subtracted from your dollar balance, You would then have fewer dollars to use for air time.
All costs for the purchase of features on Pick Your Plan accounts are added to your regular payments and become an addition to your regular recurring charge. Some states require taxes to be subtracted from your existing balance while other states require that the taxes be added to the regular payments.