In a situation where some taxpayers have problems validating invoices due to communication problems and, on the other hand, the slowness of the linked tax ledger hinders them in their work, I would like to propose an alternative security solution. Invoices issued offline should contain information on the taxable person's aggregate turnover during the calendar year, separately for each VAT rate. The information could possibly also be encrypted, although the taxable person's turnover is not a business secret. Another solution would be to show only the last few figures of the total turnover, taking into account the maximum reasonable value of each invoice. This system would still allow the last invoice or the last few invoices issued to be deleted, but would certainly be relatively secure. It would be easy to implement on all computerised cash registers.