VBA-copy row data to corresponding sheet

JDAV44 

Try this (it is not the fastest, but it should work).

Sub SplitData()
    Const IDCol = "A"
    Const HeaderRow = 1
    Const FirstRow = 2
    Dim SrcBook As Workbook
    Dim SrcSheet As Worksheet
    Dim TrgSheet As Worksheet
    Dim SrcRow As Long
    Dim LastRow As Long
    Dim TrgRow As Long
    Dim ID As String
    Application.ScreenUpdating = False
    Set SrcSheet = Worksheets("ALLDATA")
    LastRow = SrcSheet.Cells(SrcSheet.Rows.Count, IDCol).End(xlUp).Row
    For SrcRow = FirstRow To LastRow
        ID = SrcSheet.Cells(SrcRow, IDCol).Value
        Set TrgSheet = Nothing
        On Error Resume Next
        Set TrgSheet = Worksheets(ID)
        On Error GoTo 0
        If TrgSheet Is Nothing Then
            Set TrgSheet = Worksheets.Add(After:=Worksheets(Worksheets.Count))
            TrgSheet.Name = ID
            SrcSheet.Rows(HeaderRow).Copy Destination:=TrgSheet.Rows(HeaderRow)
        End If
        TrgRow = TrgSheet.Cells(TrgSheet.Rows.Count, IDCol).End(xlUp).Row + 1
        SrcSheet.Rows(SrcRow).Copy Destination:=TrgSheet.Rows(TrgRow)
    Next SrcRow
    Application.CutCopyMode = False
    Application.ScreenUpdating = True
End Sub