Insert dynamic formulas into cells

Hi guys.

I am trying to write a VBA code that would insert a formula in a cell if another cell meets a condition. E.g. If R3 = "Academic" Then M3 = "n/a". Otherwise, M3 assumes the following formula:

Formula:

=IFERROR(IF(OR(K3=I3, AND(K3<I3,K3+L3=I3),OR(ISBLANK(K3:L3),L3=0), K3+L3>I3), 0, I3-K3-L3), "")

Currently I managed to get this working with the following code:

If Target.Column = 18 Then
    Select Case Target.Value
    Case "Academic"
        Target.Offset(, -5) = "n/a"
        Target.Offset(, -5).HorizontalAlignment = xlCenter
Case Else
        Target.Offset(, -5).Formula = "=IFERROR(IF(OR(K3=I3, AND(K3<I3,K3+L3=I3),OR(ISBLANK(K3:L3),L3=0), K3+L3>I3), 0, I3-K3-L3), """")"
End Select
End If

So what happens is that cell, say, M10 is using the formula based on row 3 instead of updating the formula to the current row, which is 10 in this case.

What's the best way of doing it?

I appreciate any help.