File with an .XLTX extension contains an XLSX spreadsheet template, stored in an open format based on XML Open format, available from Microsoft Excel 2007. It enables creating a new file based on settings and information about a given setup. Along with the software, there are templates provided to create basic documents, such as lists, calendars, expenditure schedules.

XLTX format substituted previously utilised XLT binary format. It offers backward compatibility, provided earlier software versions has the Open XML plugin installed. It enables storing documents of same properties and formats.