Flattened PDFs: Why They Invalidate E-Signatures

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How to ensure your PDFs have valid legally binding signatures

What is a flattened PDF:

Flattening a PDF involves merging or embedding all the document’s elements into a single layer, including e-signatures. Once flattened, the PDF becomes a static image, making individual elements inaccessible for validation. 

The significance of avoiding flattened PDFs for e-signatures:

A PDF with legally binding e-signatures applied to it as having multiple layers of authentication that creates a traceable record for who signed, the document, where and at what time. When you flatten a PDF, these layers are stripped away, potentially invalidating the signatures.

Flattening PDFs can happen inadvertently, posing risks for businesses:

You might not be aware that your current signature solutions may not be the most suitable. Certain providers offer only flattened signatures, which lack legal validity. Additionally, there’s a risk of human error, as users might inadvertently flatten PDFs, leading to unforeseen complications.

Examples of how user flatten PDFs:

  • Opening a PDF without Adobe Acrobat reader, for example using Mac Preview, and saving it.
  • Printing and marking up a PDF, then scanning and uploading it as a new saved file.
  • Using “Print to PDF” to save a copy of the PDF.
  • Using Adobe Acrobat Reader Pro product that allows for editing, then making changes


Mitigating the risk of generating a flattened PDF and invalidating e-signatures involves:

  1. Opting for advanced e-signature solutions such as eZsign, which feature robust validation mechanisms, ensuring a Level 4 assurance for secure and reliable electronic signatures.
  2. Establishing specific processes at your company, such as creating PDFs only with Adobe Acrobat Reader and avoiding file format alterations.


📌 Pro Tip:

When receiving documents via email, download them directly without opening them to preserve their status. Opening the file in Adobe Acrobat Reader is safe, but using Adobe Acrobat Reader Pro for edits may invalidate signatures. 

eZsign clients:

Learn more in our Validity of an Electronic Signature Online Documentation article.