If IsNull([üadoszam]) Then
          Else
            If Len([üadoszam]) = 13 Then
              If Mid$([üadoszam], 11, 1) = Chr(45) And Mid$([üadoszam], 9, 1) = Chr(45) Then
                a = Left([üadoszam], 1)
                b = Mid$([üadoszam], 2, 1)
                c = Mid$([üadoszam], 3, 1)
                d = Mid$([üadoszam], 4, 1)
                e = Mid$([üadoszam], 5, 1)
                f = Mid$([üadoszam], 6, 1)
                g = Mid$([üadoszam], 7, 1)
                h = Mid$([üadoszam], 8, 1)
                i = Mid$([üadoszam], 10, 1)
                j = Mid$([üadoszam], 12, 1)
                k = Mid$([üadoszam], 13, 1)

                If IsNumeric(a) = -1 And IsNumeric(b) = -1 And IsNumeric(c) = -1 And IsNumeric(d) = -1 And IsNumeric(e) = -1 And IsNumeric(f) = -1 And IsNumeric(g) = -1 And IsNumeric(h) = -1 And IsNumeric(i) = -1 And IsNumeric(j) = -1 And IsNumeric(k) = -1 Then
                   Else
                    MsgBox "Az adószám érvénytelen karaktert tartalmaz!"
                    Exit Sub
                End If
 
                x = 9 * a + 7 * b + 3 * c + d + 9 * e + 7 * f + 3 * g
                y = Right(x, 1)

                  If h = Right(10 - y, 1) Then
                    Else
                     MsgBox "Hibás adóazonosító szám!"
                     Exit Sub
                  End If
               Else
                 MsgBox "Rossz karakter az elválaszó jel helyén!"
                 Exit Sub
               End If
             Else
                MsgBox " Hibás karakterszám az adószámban!"
                Exit Sub
             End If
              
         End If