Failure of the tax bureau’s signature verification system will also cause signature verification to fail.

After the invoice is issued and uploaded to the Internet, the tax digital certificate will fail to add a digital signature to the electronic invoice. Failure of the tax bureau's signature verification system can also cause signature verification to fail. These are caused by non-human factors and are rare, but currently unavoidable. Failed invoices must be canceled and reissued. Invoices that span multiple months must be supplemented by the tax bureau stub.