According to my experience in dealing with the IRS for many years, the IRS has managed all bills that belong to the input tax of value-added tax except purchase invoices. Don't believe what you see, such as freight invoices, invoices for waste materials, customs value-added tax payment books, etc.

Their biggest headache now is this purchase invoice. On the one hand, it is filled in by hand. On the other hand, because there are many customers and sellers, they are also thinking about countermeasures and gradually stop issuing purchase invoices. At present, most manual purchase invoices have been cancelled. Some areas have stopped using the computer version of ordinary ticket purchase.

The future trend is to use online purchase invoices, so that when enterprises use purchase invoices, the tax bureau will grasp and monitor the income in real time.

I wonder if this explanation will satisfy you.