Group 1 - The article discusses the tax obligation timing for taxpayers selling taxable products, specifying different scenarios for direct payment, credit sales, prepayment, and collection through banks [2] - For direct payment sales, the tax obligation occurs on the day the payment is received or the invoice is issued [2] - In cases of credit sales, the tax obligation is determined by the contract payment date or the day the taxable product is dispatched if no written contract exists [2] - For prepayment sales, the tax obligation arises on the day the taxable product is dispatched [2] - When using collection through banks, the tax obligation occurs on the day the taxable product is dispatched [2]