code: private boolean checkAtVatId(final String pvatId) {
      final int checkSum = pvatId.charAt(10) - '0';
      final int sum = pvatId.charAt(3) - '0' + squareSum((pvatId.charAt(4) - '0') * 2)
          + pvatId.charAt(5) - '0' + squareSum((pvatId.charAt(6) - '0') * 2) + pvatId.charAt(7) - '0'
          + squareSum((pvatId.charAt(8) - '0') * 2) + pvatId.charAt(9) - '0';
      final int calculatedCheckSum = (96 - sum) % 10;
      return checkSum == calculatedCheckSum;
    }
docs: check the VAT identification number, country version for Austria.
  
  @param pvatId vat id to check
  @return true if checksum is ok