code: private boolean checkItVatId(final String pvatId) {
      final int checkSum = pvatId.charAt(12) - '0';
      final int sum = pvatId.charAt(2) - '0' + squareSum((pvatId.charAt(3) - '0') * 2)
          + pvatId.charAt(4) - '0' + squareSum((pvatId.charAt(5) - '0') * 2) + pvatId.charAt(6) - '0'
          + squareSum((pvatId.charAt(7) - '0') * 2) + pvatId.charAt(8) - '0'
          + squareSum((pvatId.charAt(9) - '0') * 2) + pvatId.charAt(10) - '0'
          + squareSum((pvatId.charAt(11) - '0') * 2);
      final int calculatedCheckSumIt = 10 - sum % 10;
      return checkSum == calculatedCheckSumIt;
    }
docs: check the VAT identification number, country version for Italy.
  
  @param pvatId vat id to check
  @return true if checksum is ok