What is .XLTM file?
Template file created by Microsoft Excel, a spreadsheet program; contains default settings and layout properties for a macro-enabled spreadsheet; used to create a new macro-Enabled workbook (.XLSM file) that uses the Open XML format, which was introduced in Microsoft Office 2007.
XLTM files can be opened in Excel 2007 or later for Mac, or by Excel 2008 or later for Mac. They may also be opened by previous versions of Excel with Open XML component support.
NOTE: The difference between XLTM and .XLTX files is that XLTX files cannot be used to generate spreadsheets that enable macros.
Recommended Software Programs to open .XLTM file