i am trying to create a simple code (before i make it more complicated) but i
fall on the first hurdle.

what is wrong with this?

Public Function returndate(inidate As Date) As Date

Dim calcdate As Double

calcdate = CDbl(inidate + 5)
On Error GoTo Errfunction
Application.Worksheets("Dates Lookup").Range("D6").Value = calcdate

Errfunction:

MsgBox Err.Description
MsgBox Err.Number

End Function