Hi, Thanks so much for your hel - im getting really close to solving my problem.

Private Sub CheckBox1_Click()
If CheckBox1.Value = True Then


Sheets("Sheet1").Range("J4:J40").FormulaArray = "=IFERROR(INDEX(C$2:C$14, SMALL(IF($B$2:$B$14=1, ROW($B$2:$B$14)-1),ROWS(G$2:G2))),"""")"
Sheets("Sheet1").Range("J4:J40").Columns().AutoFit
ElseIf CheckBox1.Value = False Then
Range("J4:J40").Value = " "
End If

End Sub

I just need the (G$2:G2) to occur sequentially {e.g. ((G$2:G3), (G$2:G4)), (G$2:G5)) etc}when the formula is repeated across the rane. Is this possible?