Legal analysis: there is no limit to the number of invalid invoices per month, but invalid invoices can only be invalidated in the month when invoices are issued, and cannot be invalidated after one month.

Legal basis: Supplementary Notice on Amending the Provisions on the Use of Special VAT Invoices

(1) Special scope of application of voided VAT

General taxpayers issue special invoices, sales returns, billing errors, etc. in the current month. If the returned invoice is received and deducted to meet the conditions for invalidation, it shall be deemed invalid; If an error is found during issuance, it can be invalidated immediately.

(2) Conditions for voiding special VAT invoices

Invalid VAT invoices must meet the following conditions:

1. The collection and deduction time of the returned invoice does not exceed the month when the seller issues the invoice;

2. The seller did not copy the tax control (that is, it was not in the anti-counterfeiting tax control system, and the IC card or IC card and floppy disk copied the billing data) and did not keep an account;

3. The purchaser is not authenticated or the authentication result is "taxpayer identification number is not authenticated" or "special invoice code and number are not authenticated".