Excel headers and footers don't evaluate worksheet formulas. If you type =TEXT(TODAY(),"mmmm") into a header, Excel treats it as plain text and prints exactly what you typed.

You have a few options:

   - Use the built-in header codes such as &D for the current date, but these won't give you just the month name.
   - Link the header to a cell using VBA. For example, if cell A1 contains =TEXT(TODAY(),"mmmm"), a macro can set the header to the value of A1:
    
     ActiveSheet.PageSetup.CenterHeader = Range("A1").Value

If you don't want to use VBA, place the month in a cell at the top of the worksheet and include that row in the print area so it appears on every printed page.
Unfortunately, there is no built-in way to use worksheet formulas directly in an Excel header or footer.

Thank you for your advice. worked out how to resolve my problem in a different way but appreciate your suggestion for future reference.