You can pay in advance every time you invoice, or at the end of the month.

Advance tax refers to the tax that needs to be paid in advance for construction, installation and real estate services in accordance with the provisions of the tax law. In other words, the payee needs to pay taxes in advance when he receives the advance payment and obtains the voucher for the advance payment. Therefore, the invoice should be issued first, and then the tax paid in advance should be declared.