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If I stamp COPY on a digitally signed contract, does that affect the signature?

Yes. A digital signature guarantees the file has not changed since it was signed, and adding a watermark is a change, so signature-checking software will show the stamped copy as modified after signing. That happens with any tool, not just this one. The answer is to keep the signed contract untouched and stamp a separate copy for sharing, or to add the mark before the document is signed.

Published · 3 min read

Why people stamp a signed contract

Common cases: you want to send the contract to an accountant, adviser or partner for reference only, and make it plain that this is a reading copy, not the original. Or you are filing a copy in a shared archive and want 'Archive copy' on it. The word COPY or 'For information only' on the pages stops anyone confusing the original with the copies in circulation.

What happens technically

A digital signature is a fingerprint calculated from the file's content at the moment of signing. PDF watermark adds the mark and saves the file again, so the content changes and the fingerprint no longer matches. Open the copy in software that checks signatures and it will report the signature as invalid, or the document as altered after signing.

In most cases the tool detects that the file carries a signature and shows a warning when you open it: the file appears to contain a digital signature and any modification may invalidate it. It does not stop you going ahead, because stamping a reading copy is perfectly legitimate as long as the original is kept.

The right approach for your situation

  • Already signed and you want to share it for reference: stamp a copy and keep the signed original somewhere safe. The tool never edits the original; it downloads a new file whose name ends in watermarked.
  • Not yet signed and you want the mark to be part of it, such as 'Draft 2' or 'Second party copy': add the mark first, then sign the stamped file. The signature then protects the mark too.
  • The other party asks for 'the signed contract': send the original with no mark, since a stamped copy will fail verification.

Steps to stamp a reading copy

  1. Duplicate the signed contract file and put the original aside.
  2. Open the duplicate in the watermark tool. The signature warning appears, which is expected.
  3. Type 'For information only' or COPY, with low opacity and a placement that does not cover the clauses or any visible signatures.
  4. Download the stamped copy and send it, with a line saying you hold the signed original.

Common questions

Does the tool re-sign the file after stamping?

No, the tool does not sign files. Re-signing can only be done by the signer with their signing software.

What about a drawn or scanned signature, not a digital one?

A drawn or scanned signature is part of the page and is not affected by saving. Just make sure the mark does not cover it.