GST

How to verify the digital signature on a GST REG-06 certificate

Updated May 2026 · 5 min read

When you register for GST, the portal hands you a Registration Certificate in Form GST REG-06. It looks like an ordinary PDF, but it carries a digital signature applied on behalf of the Goods and Services Tax Network (GSTN). That signature is what makes the certificate legally trustworthy — provided it actually checks out. If a landlord, bank or new supplier asks you to "prove your GST certificate is genuine", this is how you do it.

Why your GST certificate shows "Signature Not Verified"

Open REG-06 in Adobe Reader and you will very likely see a yellow bar: "At least one signature has problems" or "Signature validity is unknown". It rattles a lot of business owners, but it almost never means the certificate is fake. Adobe simply hasn't been told to trust the Indian root certificate that GSTN's signing certificate ultimately chains back to. It is a trust-configuration gap on your computer, not a defect in your certificate. We explain the difference in detail in our fix "Signature Not Verified" guide.

The fastest way to verify it

Download your REG-06 PDF from the GST portal (Services → User Services → View/Download Certificates).
Open our PDF signature verifier and upload the file.
Click Verify signature. In a few seconds you'll see a Green, Amber or Red verdict along with the signer and the issuing authority.
A Green result means the certificate is intact and signed by a trusted authority — even if Adobe called it "unknown".

Because our tool already trusts every Indian CCA root, it confirms the same signature your desktop reader was unsure about. Your file is deleted automatically within two hours.

What the signature actually proves

A valid signature on REG-06 proves two independent things at once: first, that not a single byte of the certificate has been altered since it was issued; and second, that it was signed under an authority that traces up to India's Controller of Certifying Authorities. If someone edited the GSTIN, the trade name or the address in a PDF editor, the integrity check would fail and you'd get a red verdict. That is exactly why a digitally signed certificate is far stronger evidence than a printout or a screenshot.

Verifying inside Adobe Acrobat (optional)

If you want Acrobat itself to show the green tick, right-click the signature, choose Show Signature Properties → Show Signer's Certificate → Trust, add it to your Trusted Certificates and enable "use as a trusted root", then validate again. Our step-by-step guide to verifying a PDF signature walks through every click.

Working with GST paperwork day to day

Verifying certificates is only half the compliance story — most businesses also spend time raising GST-compliant tax invoices. If that's you, our sister project Invoice Generators is a free GST invoice generator built for Indian businesses, so you can create clean, compliant invoices in minutes and keep your GST documentation tidy.