Changes to lookup data to only affect ROWs with todays date or greater instead of all data

Can't think of any way of doing this that doesn't involve replacing the formulae for days past with a static value.

You could do this using the Workbook_Open() event, Worksheet_Change() event and others, but the workbook would then have to be a macro-enabled one. For example:

Private Sub Workbook_Open()
    Dim resp As Variant
    resp = MsgBox("Would you like to prevent past data from being changed?", vbYesNo, "Question")
    If resp = vbYes Then
        With Arkusz1
        
            ' first sort so we know things are in chronological order
            ActiveWorkbook.Worksheets("Sheet1").Sort.SortFields.Add2 Key:=Range("C3:C45"), SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
            With ActiveWorkbook.Worksheets("Sheet1").Sort
                .SetRange Range("B2:E45")
                .Header = xlYes
                .MatchCase = False
                .Orientation = xlTopToBottom
                .SortMethod = xlPinYin
                .Apply
            End With
            
            ' loop through the dates until we get to today's date:
            For Each d In .Range("C3:C45")
                ' replace formula with value if earlier than today
                If d.Value < Date Then
                    d.Offset(0, 2).Value = d.Offset(0, 2).Value
                Else: Exit For
                End If
            Next d
        
        End With
    End If
    
End Sub

Would that do the trick?

Tim

NB You could put your "Rota" in a table and use qualified table references instead of hard-coding the ranges. Then the data could change without messing up the VBA.

Glad it's sorted, and thanks for the rep.

Tim