telekomSum = WorksheetFunction.SumIf(TKSheet.Range(bereichsSpalte & "2:" & bereichsSpalte & lastSetTelekomRow), _
          bereichsWert, TKSheet.Range(telekomSumColumn & "2:" & telekomSumColumn & lastSetTelekomRow))
novatecSum = WorksheetFunction.sum(NTSheet.Range(tCol & "2:" & tCol & lastSetNovatecRow))

closeflag = True

If Abs(telekomSum - novatecSum) >= 0.01 Then
    ' Error Message
    MsgBox "Summen stimmen nicht überein. " & _
    "Bitte überprüfen Sie die eingepflegten Verträge und Mobilfunknummern:" & vbCrLf & "NovaTec: " & _
    novatecSum & "€" & vbCrLf & "Telekom: " & gesamt & "€" & vbCrLf & vbCrLf & _
    "Doppelte Mobilfunknummern wurden in Ihrem Excel-Sheet markiert." & vbCrLf & _
    "Diese sind Hauptfehlerursache. Bitte beseitigen Sie eventuell doppelte Einträge" & _
    vbCrLf & vbCrLf & "Außerdem wurden in der Angegebenen Rechnung alle einbezogenen Subtotalen markiert" _
    , vbExclamation, "INFO:"
    
    ' Prevent closing of imported file
    closeflag = False
    
    ' Troubleshooting help for user
    NTSheet.Range("C2:C" & lastSetNovatecRow).Select
    Selection.FormatConditions.Delete
    Selection.FormatConditions.Add Type:=xlCellValue, Operator:=xlDuplicate
    Selection.FormatConditions(1).Interior.Color = RGB(255, 40, 80)
End If

If closeflag Then
    ' Close without saving
    Workbooks(2).Close (False)
End If

' Show compared values in the opened worksheet
NTSheet.Range(tCol & lastSetNovatecRow + 2).Value = novatecSum
NTSheet.Range("D" & lastSetNovatecRow + 2).Value = "NovaTec Summe"
NTSheet.Range(tCol & lastSetNovatecRow + 3).Value = telekomSum
NTSheet.Range("D" & lastSetNovatecRow + 3).Value = "Telekom Summe"
NTSheet.Range(tCol & lastSetNovatecRow + 4).Formula = "= " & tCol & lastSetNovatecRow + 2 & "-" & tCol & lastSetNovatecRow + 3
NTSheet.Range("D" & lastSetNovatecRow + 4).Value = "Differenz:"
End Sub

Well then, here's my first question on this site. I was assigned the task of copying some subsums from a given EXCEL-Sheet into the executing EXCEL-Sheet.

Enough talk, here's the code. I am inserting <hr> to divide the code into it's logical parts.. that should make it more readable:

I was assigned the task of copying some subsums from a given EXCEL-Sheet into the executing EXCEL-Sheet.

What can be said about the readability and maintainability?

Enough talk, here's the code. I am inserting <hr> to divide the code into it's logical parts. That should make it more readable.