How to Set Word Default Save Format to OOXML Strict Versus Transitional

When you save a document in Word, the default format is the Transitional version of Office Open XML or OOXML. This format ensures broad compatibility with older versions of Word. However, the Strict version of OOXML follows the ISO 29500 standard more closely and is required for some enterprise or government compliance policies. This article explains the difference between OOXML Strict and Transitional and shows you how to set Word to save documents in your preferred format by default.

What Is OOXML Strict and Transitional

Office Open XML or OOXML is the file format used by Word for .docx files. There are two versions: Transitional and Strict. Transitional OOXML was introduced in Office 2007 and is the default format for all current Word versions. It allows some elements that are not part of the ISO 29500 standard, such as older drawing objects and compatibility settings. Strict OOXML conforms fully to ISO 29500:2008 and does not permit those legacy elements. Strict files are smaller and more interoperable with other ISO-compliant applications, but they cannot be opened by Word 2007 or earlier. Word 2010 and later can open both formats.

The choice between Strict and Transitional depends on your audience. If you share documents with users on Word 2007 or with applications that only support Transitional, keep the default. If you need strict regulatory compliance or maximum file size reduction, switch to Strict. The format also affects macro-enabled documents: Transitional .docm files are distinct from Strict .docm files, but both can contain VBA macros.

Steps to Change the Default Save Format in Word

Follow these steps to set Word to always save new documents in either Transitional or Strict OOXML format. The setting applies to all new documents you create after the change.

1. Open Word Options
   Click File on the ribbon, then click Options at the bottom of the left pane. The Word Options dialog box opens.
2. Go to the Save category
   In the left column of the dialog box, click Save. The right pane shows all save-related settings.
3. Locate the Save files in this format drop-down
   Under the “Save documents” section, find the label “Save files in this format”. The drop-down list is directly below it. The current default is shown, usually “Word Document (.docx)” which is Transitional.
4. Select your preferred format
   Click the drop-down arrow and choose one of the following:
   – Word Document (.docx): Transitional OOXML, compatible with Word 2007 and later.
   – Strict Open XML Document (.docx): Strict OOXML, compatible with Word 2010 and later.
   – Word Macro-Enabled Document (.docm): Transitional OOXML with macro support.
   – Strict Open XML Macro-Enabled Document (.docm): Strict OOXML with macro support.
   If you never use macros, choose the non-macro version. If you use macros, choose the corresponding .docm option.
5. Apply the setting
   Click OK at the bottom of the dialog box. All new documents you create from now on will use the selected format. Existing documents are not affected.

Things to Avoid When Changing the Default Save Format

Do not change the format for a single document and expect it to persist

If you manually save a document as Strict using File > Save As, that document uses Strict. But the default for new documents remains Transitional unless you change the option in Word Options. Always check the default setting if you want all future documents to use a specific format.

Strict files do not open in Word 2007

Word 2007 cannot open Strict OOXML files at all. If you share documents with users on Word 2007, keep the default set to Transitional. Otherwise, recipients will see an error message and will not be able to open the file without a compatibility pack.

Macros require the correct .docm extension

If your document contains VBA macros, you must save it as a macro-enabled document. Selecting “Strict Open XML Document (.docx)” will strip all macros from the file. Use “Strict Open XML Macro-Enabled Document (.docm)” to preserve macros. The same applies to Transitional: choose “Word Macro-Enabled Document (.docm)”.

Do not confuse Strict with the OpenDocument format

Strict OOXML is not the same as OpenDocument Format or ODF. ODF is used by LibreOffice and Google Docs. Word can save in ODF, but that is a separate option in the same drop-down list. If you need ODF, select “OpenDocument Text (.odt)” instead.

Item	OOXML Transitional	OOXML Strict
ISO standard	ECMA-376, not fully ISO 29500	ISO 29500:2008 compliant
Word compatibility	Word 2007 and later	Word 2010 and later
File size	Slightly larger due to legacy elements	Smaller, no legacy elements
Macro support	.docm extension	.docm extension (Strict Macro-Enabled)
Default in Word	Yes	No, must be changed manually
Interoperability	Broad, including older Office versions	Narrower, but better with ISO-compliant apps

Now you can set Word to save all new documents in either OOXML Strict or Transitional format. Use File > Options > Save to choose the format that fits your sharing and compliance needs. If you share documents with users on Word 2007, keep Transitional selected. For strict regulatory environments or smaller file sizes, switch to Strict. After changing the default, verify that a new document saves with the correct extension by creating a blank file and checking its properties.