In short: For law firms, electronic signing is valid across the EU under eIDAS, and most engagement letters, retainers and routine correspondence can be signed at an advanced level. The key exception is any document under a statutory written-form requirement, where a qualified electronic signature (QES) is generally needed to replace a wet-ink signature. A few acts that require notarial form cannot be signed electronically at all.
For a law firm, a signature is evidence. If a client later disputes a mandate or an agreement, the firm needs to show who signed, that the document was unchanged, and that the signature carries the right legal weight. That is exactly what electronic signatures for law firms deliver, provided the firm picks the correct level for each document.
This guide walks through which legal documents a firm can sign electronically, when the written-form requirement forces a qualified signature, and how to run secure client onboarding without slowing the engagement.
The three signature levels explained for legal work
Under eIDAS, a simple electronic signature (SES) is any electronic mark indicating agreement; it carries little independent proof of identity. An advanced electronic signature (AES) is uniquely linked to the signer and detects any change to the document after signing, which makes it suitable for most contractual work. A qualified electronic signature (QES) adds a qualified certificate and a qualified signature creation device, and it is the only level that eIDAS treats as legally equivalent to a handwritten signature across the EU.
For legal practice, the distinction that matters most is evidentiary weight. A QES shifts the practical burden in a dispute, because its link to a verified identity is hard to contest, while an AES still gives strong tamper-evidence for everyday agreements.
Which documents can law firms sign electronically
Most of a firm's paperwork can move to electronic signing, but a handful of acts cannot. Use this checklist to sort documents quickly, then confirm against the relevant national law:
- Routine and low-risk: engagement letters, fee agreements, cover letters and internal approvals, where SES or AES is proportionate.
- Written-form documents: agreements where the law requires written form generally need a QES to replace a handwritten signature and stay valid.
- High-value or contentious agreements: use a QES for the strongest evidence of identity and integrity if the matter is ever litigated.
- Court and authority filings: follow each court's or authority's own electronic filing rules, which may prescribe a specific signature or submission channel.
- Notarial-form acts: certain transactions require notarisation and cannot be completed with a standard electronic signature; check before promising a client a fully digital process.
When a document sits under a written-form requirement or carries real dispute risk, default to a qualified electronic signature. For everything else, an advanced signature usually keeps the file moving without over-engineering.
Client onboarding with electronic signatures for law firms
Onboarding is where identity proof and signing meet. A clean process protects the firm and speeds the first signature:
- Verify client identity up front using a trusted eID or a compliant remote identity check, so a later QES is anchored to a confirmed person.
- Send the final engagement documents as a locked file so nothing can change before signing.
- Let clients sign remotely at the required level from any device, without needing a card reader.
- Apply a qualified timestamp and archive in PAdES, so the signed PDF stays verifiable for the firm's full retention period.
This removes the courier and print-sign-scan loop that often delays the start of a mandate, and it leaves a complete record of who agreed to what.
Cross-border recognition and the written-form question
A qualified electronic signature must be recognised in every EU member state, which matters for firms acting across borders or for international clients. An AES or SES, by contrast, is assessed on its own merits and may be weighed differently from one jurisdiction to another.
The recurring question in practice is whether a given document carries a statutory written-form requirement. If it does, treat a QES as the safe default; if it does not, an advanced signature is usually enough. Documenting that decision for each document type turns an ad hoc judgement into a repeatable firm policy.
Used consistently, electronic signatures for law firms shorten every file from first contact to signed agreement while strengthening the evidence behind each one.
How primesign helps
primesign is an Austrian qualified trust services provider offering qualified signatures, seals and timestamps under eIDAS. Lawyers and clients can apply a qualified electronic signature remotely from any device, with results archived in PAdES for long-term validation, so a firm can move from engagement letter to signed agreement without paper.
Want engagement letters and contracts signed to the right standard, without the courier?