The two ways to sign a Word document

Microsoft Word offers two methods to sign a document digitally: a signature line that shows a visual signature placeholder, and a digital signature that encrypts the document and marks it as read-only once signed. A signature line is what most people use for contracts, agreements, and formal letters — it looks like a traditional signature block and lets others see who signed and when. A digital signature is more technical and is used when you need to prove the document hasn't been altered since you signed it.

The method you choose depends on what the document is for. If you're signing a contract or agreement that will be printed or shared, use a signature line. If you need to prove the document is authentic and unchanged, use a digital signature. Most everyday documents — purchase orders, approval forms, letters — work fine with a signature line.

Key Takeaways

  • A signature line creates a visual placeholder where you can type, draw, or insert an image of your signature.
  • To add a signature line, go to Insert > Signature Line and fill in your name, title, and email address.
  • Once you sign a signature line, you can continue editing the document unless you also apply a digital signature.
  • A digital signature locks the document and proves it hasn't been changed since you signed it, but requires a certificate from your computer or a third-party provider.
  • Most people use signature lines for everyday documents; digital signatures are used when legal proof of authenticity matters.

How to add and sign a signature line

Open your Word document and place your cursor where you want the signature to appear. Go to the Insert tab at the top, then click Signature Line (it's in the group labeled "Text"). A dialog box will open asking for your name, title, and email address. Fill in at least your name, then click OK. Word will insert a line with an X placeholder that looks like a traditional signature block.

To actually sign the signature line, double-click on it. A signing dialog will open. You have three options: type your name, draw your signature with your mouse or touchpad, or insert an image of your signature. Type your name if you want a clean, printed look. Draw your signature if you want something that looks handwritten — use your mouse or a stylus on a touchscreen. Insert an image if you've already scanned or photographed your signature. Choose whichever matches what you need, then click Sign.

After you sign, the signature line will display your name or image, and the document remains editable. You can still make changes to the text, add more signatures, or print it. The signature line is just a visual marker that you've reviewed and approved the document.

How to apply a digital signature

A digital signature is different from a signature line. It encrypts the document and prevents anyone from changing it after you sign. To add a digital signature, go to File > Info, then click Protect Document and select Add a Digital Signature. Word will ask you to choose a certificate — this is a file on your computer that proves your identity.

If you don't have a certificate, you'll see a message saying so. You can get one from your organization's IT department, or you can purchase one from a third-party provider like DigiCert or Sectigo. Some organizations issue certificates automatically to employees. If you're working on your own, ask your IT support whether a certificate is available to you. Once you have a certificate, select it from the list, add a reason for signing if you want, and click Sign.

After you apply a digital signature, the document becomes read-only. Anyone who opens it will see that it's been signed and by whom, and they'll know if anyone has tried to change it since you signed. If you need to make more changes, you'll have to remove the digital signature first, edit the document, and then sign it again.

Signature line vs. digital signature: which one to use

Use a signature line for most everyday documents: contracts you're emailing, approval forms, letters, purchase orders, or anything that will be printed or shared casually. It's simple, visible, and doesn't require any special setup. People can see at a glance that you've signed it.

Use a digital signature when the document is legally sensitive or when you need to prove it hasn't been tampered with. Examples include financial documents, legal agreements that will be filed, or anything that might be challenged later. Digital signatures are also required by some industries or government processes. If you're not sure which one you need, a signature line is the safer default — it works for almost everything.

Troubleshooting common signature problems

If you can't find the Signature Line option, make sure you're on the Insert tab, not the Home tab. It's sometimes grouped under "Text" or "Explore" depending on your Word version. If the option is grayed out, the document might be in a read-only mode — try saving it with a new name first.

If you're trying to add a digital signature and Word says you don't have a certificate, you'll need to get one from your IT department or a certificate provider. This is a one-time setup. Once installed, it will appear in the certificate list every time you sign a document.

If you've already signed a document with a digital signature and need to make changes, you'll have to remove the signature first. Go to File > Info > Protect Document and look for an option to remove the signature. After you remove it, edit the document, then sign it again.

Sharing a signed document

Once you've signed a document with a signature line, you can email it, print it, or share it as a PDF without any issues. The signature stays visible and the document remains editable by others unless you've also locked it with a digital signature.

If you've applied a digital signature, the document is locked and read-only. When you share it, recipients will see that it's been signed and won't be able to change it. If they need to make changes, they'll have to ask you to remove the signature, make the edits, and sign it again. Some organizations require digital signatures on sensitive documents before they're filed or archived.

Frequently Asked Questions

Can I add multiple signatures to one document?

Yes. You can add multiple signature lines and have different people sign them. Each person double-clicks their own signature line and signs it. If you're using digital signatures, each person needs their own certificate, and the document gets signed multiple times in sequence.

What if I sign a document and then need to change it?

If you used only a signature line, you can edit the document freely — the signature line is just a visual marker. If you applied a digital signature, you'll need to remove it first, make your changes, and then sign it again. The document will show that it's been modified.

Can I use a scanned image of my signature?

Yes. When you double-click a signature line, one of your options is to insert an image. You can scan your signature or take a photo of it, save it as a file, and insert it. Make sure the image is clear and shows just your signature without extra background.

Do I need a digital signature for everyday documents?

No. A signature line is fine for most documents — contracts, approvals, letters, forms. Digital signatures are used when you need legal proof that the document is authentic and hasn't been changed. Ask whoever is requesting the signature if they need a digital signature or if a signature line is acceptable.

What happens if someone tries to change a digitally signed document?

Word will show a warning that the document has been modified since it was signed. The digital signature becomes invalid, and anyone opening the document will see that it's no longer trusted. This is why digital signatures are useful for sensitive documents — they prove the document hasn't been altered.