"it's a file that will be supplied multiple times a day so it's not feasible to convert it every time."

Why?

You have to give us more background information.

"and contains macro's causing it to be a .xlsm file."

Why not cange that macro so the file format is .txt

This Little macro opens a .xlsm file and saves it as a .txt file

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Workbooks.Open Filename:="XXXXX\YYYY.xlsm"

ActiveWorkbook.SaveAs Filename:="XXXXX\YYYY.txt", FileFormat:= _

xlText, CreateBackup:=False

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Gosta M