Sub File_name_change()
'For MN_Excel http://www.mrexcel.com/forum/excel-questions/672666-file-name-change.html
Dim filesystem As Object, myfolder As Object
Dim myfiles As Object, myfile As Object, Pastefile As Object
Dim Dte As String
Dim Strt As String
Dim cncat As String
On Error Resume Next
Set filesystem = CreateObject("Scripting.filesystemobject")
Set myfolder = filesystem.getfolder("C:\LOCATION OF THE FOLDER") 'Sets the folder where the files are
Set myfiles = myfolder.Files
Dte = "0512" 'Whatever the constant date is
For Each myfile In myfiles
Strt = myfile.Name
cncat = Strt & Dte
myfile.Name = cncat & ".xls" 'Choose the file extension that suits.
Next
End Sub