VBA If Vlookup

without your file?

I've figure out how to do it differently. Maybe not the best way, but it works.

lastRow = Range("A" & Rows.Count).End(xlUp).Row
Range("G2:G" & lastRow).Formula = "=IFERROR(VLOOKUP(E2,Min_Months,IF(VLOOKUP(B2,ModelSplit,2,0)=""WH"",3,IF(VLOOKUP(B2,ModelSplit,2,0)=""CB"",4,0)),1),0)"
Range("G2:G" & lastRow).Copy
Range("G2:G" & lastRow).PasteSpecial xlPasteValues

Thank you for your help on this.