Signing invoices and quotes electronically
Typed and drawn signatures are legally recognised in most countries. Here is what they prove, what they don’t, and when you need a certificate-based digital signature instead.
What the law says
- United States: the ESIGN Act says a signature or contract relating to interstate commerce may not be denied legal effect solely because it is in electronic form. Most states also adopted the Uniform Electronic Transactions Act.
- European Union: eIDAS Article 25 says an electronic signature shall not be denied legal effect or admissibility as evidence solely because it is electronic. Only a qualified electronic signature automatically has the same effect as a handwritten one.
- United Kingdom: electronic signatures are admissible under section 7 of the Electronic Communications Act 2000, and the Law Commission’s 2019 report confirmed they can be used to execute documents where a signature is required, with some exceptions such as certain deeds and wills.
Some documents are carved out almost everywhere (wills, certain real-estate transfers, court documents). Invoices, receipts, quotes and work orders are not among them.
Electronic vs digital signatures
| Electronic signature (typed or drawn) | Digital signature (certificate) | |
|---|---|---|
| What it is | An image or mark showing intent to sign | Cryptographic seal over the document’s hash |
| Shows who signed | By context (email trail, who sent it) | Certificate identifies the signer |
| Detects edits | No | Yes, any change breaks it |
| Good for | Quotes, receipts, work sign-offs, delivery notes | High-value contracts, regulated filings |
Why a certificate-based digital signature catches tampering
A drawn or typed signature is an image: anyone can edit the numbers next to it. A cryptographic digital signature signs a fingerprint (hash) of the exact document. Change one character below (try 1,250 → 7,250) and watch the fingerprint no longer match the one that was signed.
✕ 0 of 64 characters changed. A PDF reader would report this signature as invalid.
Making electronic signatures stronger
- Send and receive signed documents by email, so there is a record of who sent what, when.
- Date every signature (Invoice Studio adds the signing date automatically).
- Keep the exported PDF unchanged; if something must change, issue a new version with a new number.
- For a certificate-based signature, open the exported PDF in a reader that supports digital IDs and sign it there.
Questions
Is a drawn signature on a PDF legally valid?
In the US, EU and UK, an electronic signature cannot be refused legal effect merely because it is electronic (ESIGN Act, eIDAS Article 25, Electronic Communications Act 2000). Whether it proves what you need in a dispute depends on the evidence around it, such as emails showing who sent and accepted the document.
What is the difference between an electronic and a digital signature?
An electronic signature is any electronic mark of intent to sign: a typed name, a drawn image, a checkbox. A digital signature is a specific cryptographic method using a certificate that makes any later change to the document detectable.
Does Invoice Studio create certificate-based digital signatures?
No. It creates electronic signatures (typed or drawn images) embedded in the PDF. For certificate-based signing, open the exported PDF in a tool that supports PDF digital signatures with your own certificate.
Do invoices need to be signed?
Generally no. HMRC’s and the EU’s required invoice contents do not include a signature. Some clients or countries ask for signed and stamped invoices as internal policy.
Sources
- US ESIGN Act, 15 U.S.C. § 7001 (Cornell LII)
- eIDAS Regulation (EU) No 910/2014, Article 25
- UK Electronic Communications Act 2000, section 7
- Law Commission (England & Wales): Electronic execution of documents (2019)
This page explains general rules; it is not legal advice.