The code below does exactly what it is meant to do without any errors.
However, I would like this ammendment to be made to it.
When the negative value in the Active sheet is added to the required row of column Z in the 'Sector Budget' sheet,
It does not overwite the existing value but rather it adds to the value.
For example, if the value entered in my Active sheet is -200, and the existing value of the relevant row in column Z of the 'Sector Budget' sheet is -100,
The value carried over from my Active sheet will add to the existing value in the 'Sector Budget' sheet and the new value will then be -300.
Can this be done?

If Target.CountLarge > 1 Then Exit Sub
' Check if the change occurred in column E or D
If Not Intersect(Target, Me.Range("E6:E305")) Is Nothing Then
    ' Verify that the entered value is numeric
    If Not IsNumeric(Target.Value) Then
        Application.EnableEvents = False
        MsgBox "Please enter a numeric value."
        Application.EnableEvents = True
        Exit Sub
    End If

    ' Prompt for confirmation
    Dim confirmation As Integer
    ' Update confirmation message
    Dim confirmationMessage As String
    If Target.Value < 0 Then
        confirmationMessage = "The Expenditure Cost will be added to the Sector Budget. Proceed?"
    Else
        confirmationMessage = "The Expenditure Cost will be deducted from the Sector Budget. Proceed?"
    End If
    confirmation = MsgBox(confirmationMessage & vbCrLf & "To ADD to/increase the budget, enter a negative value. Proceed?", vbYesNo + vbQuestion, "Confirm Deduction or Addition")

    ' Check user's response
    If confirmation = vbYes Then
        ' Proceed with deduction or addition logic
        Dim deducedCell As Range
        Set deducedCell = Target.Cells(1)
        Application.EnableEvents = False
        Dim deductionValue As Double
        deductionValue = deducedCell.Value
        Dim sectorBudgetSheet As Worksheet
        Set sectorBudgetSheet = ActiveWorkbook.Worksheets("Sector Budget")
        Dim searchValue As String
        searchValue = ActiveSheet.Range("D1").Value
        Dim matchRow As Long
        matchRow = sectorBudgetSheet.Range("A:A").Find(searchValue, LookIn:=xlValues, LookAt:=xlWhole, SearchOrder:=xlByRows, MatchCase:=False).Row
        If matchRow = 0 Then Exit Sub
        Dim currentAAValue As Double
        currentAAValue = sectorBudgetSheet.Cells(matchRow, 27).Value
        ' Check if the value is negative
        If Target.Value < 0 Then
            ' Add the negative value to column Z
            sectorBudgetSheet.Cells(matchRow, 26).Value = sectorBudgetSheet.Cells(matchRow, 26).Value + deductionValue
        Else
            ' Deduct the value from column AA
            currentAAValue = currentAAValue - deductionValue
            sectorBudgetSheet.Cells(matchRow, 27).Value = currentAAValue
        End If
        ActiveSheet.Protect Password:="edit"
    Else
        ' Restore original value explicitly
        Application.EnableEvents = False
        'Dim originalValue As Variant
        'originalValue = Target.Value
        Application.Undo
        Target.Value = Target.Value2
        Application.EnableEvents = True
    End If

    ActiveSheet.Range("K2").Calculate
    Application.EnableEvents = True
End If