private function isChecksumValid()
    {
        $countryCode = $this->getCountryCode();
        $checksum = $this->getChecksum();
        $accountIdentification = $this->getAccountIdentification();
        $numericCountryCode = $this->getNumericCountryCode($countryCode);
        $numericAccountIdentification = $this->getNumericAccountIdentification($accountIdentification);
        $invertedIban = $numericAccountIdentification . $numericCountryCode . $checksum;

        return $this->bcmod($invertedIban, 97) === '1';
    }