MS Word: How To Create Master Documents and Sub Documents

MS Word allows you to manage large documents by creating a Master Document and multiple sub-documents.

The benefit of using a Master Document is that you can structure a large document by linking a single Master document to one or more sub-documents (i.e. chapters, sections, even paragraphs) , allowing you to work on each individually without interfering with the main document. This also means you can assign out writing tasks, then simply link in the relevant chapter when it is ready.

Inserting subdocuments into a master document

Table of Contents

MS Word: How To Create Master Documents and Sub Documents
What is a Master Document in MS Word?
What are the advantages of using Master Documents?
How To Create Master Documents In Word.
Master Document Menu Options
Troubleshooting Master Documents
Best Practices: Master Documents

MS Word: How To Create Master and add Sub Documents

In this tutorial, we look at how to make a Master Document in MS Word 2016, then add, move, and update its subdocuments.
Tip: Use the same template in both the Master and Subs.

Instead of trying to maintain a single large document you can create this master document and simply point to the subsections or subdocuments, which are then included in the final compiled document. This approach offers several other advantages, notably, that you have better control over style, format, and versioning, as well as minimizing the likelihood that your Word document will crash when it gets too large.

To make a Master Document in MS Word 2016, simply name a file as the Master Document, then insert subdocuments. You can further split or merge other subdocuments

Use the following checklist to create master documents using MS Word.


In this video, we show you how to create a Master document, in particular, how to use the menu options in Word to organize and structure your documents.

What is a Master Document in MS Word?

A Master document is a MS Word file comprised of a master document and one or more sub-documents. A subdocument is a single MS Word file.

A Master document:

  • Contains a number of Subdocuments
  • Uses the same hierarchal structure similar to folders and files
  • Supports Relative and Absolute paths. Content can be stored relative or linked absolutely to the Master.

Note: The content of the subdocuments are not inserted into the master document, rather the Master document links to these files and then compiles them as a single file when you print the file.

What are the advantages of using Master Documents?

Master documents offer several advantages including the ability to:

  • Maintain a consistent style and branding across your documents
  • Reduce the likelihood that Word will crash, i.e. due to file size
  • Allow you to move sections around the master document faster
  • Edit subdocuments separately with effecting other documents
  • Automatically update the master document. Changes in the sub documents are reflected automatically in the master document.
  • Allows multiple writers to work on the same document at the same time. You can assign one section to a writer, then insert this into the ‘final’ master document.
  • Lock parts of the documents so it cannot be edited.
  • Increase productivity by creating chapters once, locking down the content, and importing this into your document.
  • Allow reviewers to review separate sections, which you can then merge into the final master document.

How To Create Master Documents In Word

Follow these steps to create a Master document to manage large MS Word files.

  1. Create your sub-documents first. Ideally, use the same template to avoid any possible rework.
  2. Backup the Sub-documents before you start.
  3. Create a new document. This is your Master.
  4. Click View, Outline. This switches the document to Outline mode, which is required if you want to import (and move around the sections.)
  5. On the Outlining tab in the Master Document group, click Show Document. This displays additional options in the Master Document group.

  1. Click Insert Sub-document to browse to the Master. Locate the first document to insert into the Master document. Insert the documents in order.
  2. Repeat to add more documents.
  3. Leave a blank line in between each Sub.
  4. If Word asks you about conflicting styles, click Yes to All. This keeps styles in the subdocuments consistent with the master document.

  1. Insert your Table of Contents.
  2. Delete all section breaks.
  3. Do not add text to the Master document except the TOC and its heading.
  4. Edit Header and Footers inside the Master.
  5. Before Printing, press CTRL+A then F9 to select all and update fields.
  6. Save and Exit the Master.

Note: You must be in Outline mode to add new sections, remove (delete) sections, or change the order.

Master Document Menu Options

When you click View, Outline, the following options are displayed on the Outlining tab. Most are self-explanatory. Here’s what they do:

  • Show Document – expands the Master Document section in the tab. This displays the Create, Insert, Unlink, Merge, Split, and Lock Document options. If starting the document, some of these will be greyed out.
  • Collapse Subdocuments – toggles between displaying the subdocument path and name and the actual subdocument content.
  • Create – changes the selected outline items into subdocuments, each major outline division becomes a separate file.

  • Insert – inserts a file into the Master Document as a subdocument. Use this approach to insert existing files into a Master Document.
  • Unlink – deletes the link to the subdocument and copies the subdocument contents into the Master Document.
  • Merge – combines multiple subdocuments into one subdocument, not one master document.
  • Split – splits a subdocument into subdocuments at the next lower organization level. For example, if your subdocument has one H1 but multiple H2s, it will create one subdocument for each H2 in the selection.
  • Lock Document – locks or unlocks the entire document or selected subdocuments.

Changing the Heading Levels

To move the section headings, such as H1s and H2s, around the master document:

  1. Click View, Outline.
  2. Use the drop-down list of Level styles and the green right/left arrows in the Outline Tools section of the Outlining tab.

Updating all Page Numbers in the Document

To update all page numbers in the document, follow these steps.

  1. Hold Ctrl+A to select the entire document.
  2. Click the Insert tab, Header & Footer, Page Number, Format Page Numbers….
  3. Click Continue from previous section.

This will update all the page numbers in the documents.

Note that if you have different numbering styles, to select the format you want, for example, Roman or Arabic.

Troubleshooting Master Documents

Do not include a ‘#’ in the file name of your sub-documents as Word will interpret this as the end of the file name. Sub-documents will not be inserted with the full and correct file name.

Best Practices: Master Documents

Follow these rules to avoid problems when using Master documents to create long documents.

1 – Use the Master For Links Only

First, create a blank Master.

Move everything else into separate subdocuments. This includes the:

  • Cover page
  • Legal text
  • Preface
  • Version History / Document History

Only use the Master to contain the links to the other files.

Note: Don’t make a Master as a Subdocument to another Master.

2 – Don’t Edit Sub-documents in the Master

If you have to edit the contents of the sub-document, then open the actual file and make the changes there.

Don’t edit subdocuments directly in the Master. This could potentially corrupt both the Master and Sub.

Close the Master when you want to edit a Sub. Word is very sensitive and struggles when large, complex documents are opened at the same time.

You don’t have to but, in my experience, Word is less likely to create issues if you open as few documents as possible at the same time. Basically, it doesn’t like ‘multi-tasking’.

3 – Delete Auto-Section Breaks

Sections can corrupt your document. Minimize this by removing redundant sections.

Of course, make sure to use sections where you need intentionally structure the document using sections.

To delete all section breaks:

  • Open the Find and Replace window.
  • Enter ^b in Find.
  • Leave Replace blank.
  • Replace All.

4 – Use the Same Template for Master and Subs

Use the same template to reduce corruption, compilation errors, and unexpected errors.

This help the Master when the styles have the same name but different formatting.

For example,

If the H1 in Sub #1 is Arial 10, but Gothic 15 in Sub #2, then Word might struggle when trying to render the content.

5 – Rebuild Documents when Master Template Changes

Rebuild your documents to prevent corruption, which typically occurs when styles conflict. This occurs when Master styles overwrite Sub styles.

6 – Rebuild the Master Periodically

Over time, the Master document will become corrupt. To maintain a healthy Master file, rebuild it periodically.