Electronic signature on a contract: what makes it binding in the UK
An electronic signature on a contract is any data in electronic form used to indicate a party's intention to be bound by its terms, legally valid for most UK business agreements under the Electronic Communications Act 2000.
An electronic signature on a contract is any data in electronic form that a party attaches to, or logically associates with, a document to indicate their intention to be bound by its terms. In the UK, the Electronic Communications Act 2000 established that electronic signatures carry the same legal weight as wet ink for the vast majority of commercial agreements, a position reinforced by the Law Commission's 2019 report on electronic execution of documents. What that report made plain is that validity does not depend on the form the signature takes. It depends on the evidence you can produce afterward: who signed, what version of the document they saw at the moment of signing, and when.
What a UK court actually looks for
If an electronic signature on a contract is challenged, a UK court examines three things. First, identity - can you show that the named party was the person who performed the signing action, not just that someone used their email inbox? Second, intent - did that person mean to be bound by this exact version of the document? A contract where the terms changed after the signing link was clicked fails this test even if both parties believed the deal was complete. Third, integrity - has the document been altered since it was signed? A cryptographic hash recorded at the moment of signing resolves this: if the hash matches the current document, nothing has changed.
These three tests are why the audit trail is more legally significant than the signature image itself. A typed name on a PDF proves none of them. An audit log that records the signer's email address, the IP address the action came from, the exact document hash at the moment of signing, and a timestamp the platform controls - that evidence is what survives a dispute.
The three tiers of electronic signature
UK eIDAS, the retained version of EU Regulation 910/2014, defines three tiers. A Simple Electronic Signature (SES) covers anything from a typed name to a scanned image pasted into a document. It is legally valid but produces little supporting evidence if challenged. An Advanced Electronic Signature (AES) is uniquely linked to the signer, capable of identifying them, and connected to the signed data in a way that detects any subsequent change to the document. This is the tier most established e-signature platforms operate at by default, and it is appropriate for routine B2B agreements. A Qualified Electronic Signature (QES) requires identity verification carried out by an accredited trust service provider - typically a video call with a government-issued ID. UK courts treat a QES as equivalent to a handwritten signature by default, shifting the burden of proof to the party challenging it. In practice QES is reserved for high-value or regulated transactions because the verification step adds significant friction.
For most B2B contracts - service agreements, supplier terms, statements of work - an AES-grade signature combined with a full audit trail is the proportionate choice.
Documents that still need wet ink
Wills (Wills Act 1837), Lasting Powers of Attorney, statutory declarations, and some property deeds requiring Land Registry registration cannot currently be executed by electronic signature under UK law. For everything else in routine commercial use, electronic signatures are valid.
Zigaflow's Contracts feature lets you send agreements for signature directly from the job record, with each document built from a document template so the version the customer signs matches exactly what was quoted. An approval workflow can ensure no contract goes out for signature until the right person inside your business has reviewed it first.