The Problem with .xlsx Files 1. The Problem with .xlsx Files If your file is saved with the .xlsx extension, Excel cannot save VBA macros. This format is designed for data and formulas only, without code support. 2. Why .xlsx Doesn't Support Macros The .xlsx format is designed for simple spreadsheets, without code or macros, for security and compatibility reasons. 3. The .xlsm Format To save macros, you must use the .xlsm format (Excel Workbook that supports macros).