Can I use four words on the check code of the received invoice?

No, it is suggested to void it and issue a new invoice.

According to Article 11 of the Provisions on the Use of Special VAT Invoices, special invoices shall be issued according to the following requirements:

1, the project is complete and consistent with the actual transaction;

2, clear handwriting, not allowed to press the line or make mistakes;

3. The invoice and deduction shall be affixed with the special invoice seal;

4. It should be issued according to the time when the VAT obligation occurs.

The buyer has the right to reject special invoices that do not meet the above requirements.