E-signature tools allow clients to sign engagement letters, accounts approval letters, tax return authorisations, and other practice documents electronically — eliminating the print-post-scan cycle that slows down document approval in accounting practices. Since HMRC accepted Advanced Electronic Signatures (AES) for client agent authorisation from 6 April 2025, fully digital authorisation workflows are now possible for tax work as well as general correspondence.

This guide covers how e-signature works in accounting, which tools meet the relevant standards, how to choose between them, and what the HMRC requirements are for tax-specific authorisations.

E-signature standards relevant to accountants

Not all e-signatures are equal. UK law (the Electronic Communications Act 2000 and the eIDAS Regulation as retained in UK law) recognises three tiers:

Simple Electronic Signature (SES): a basic digital signature — for example, clicking "I agree" in an email or typing your name. Valid for most general commercial documents but does not meet HMRC's AES requirement.

Advanced Electronic Signature (AES): uniquely linked to the signatory, capable of identifying the signatory, created using data under the sole control of the signatory, and linked to the signed data in a way that detects subsequent changes. Most professional e-signature platforms (DocuSign, Adobe Acrobat Sign, Glide) produce AES-standard signatures.

Qualified Electronic Signature (QES): the highest tier, requiring a qualified certificate issued by a trust service provider. Rarely required in accounting practice.

For most accounting firm needs — engagement letters, accounts approval, correspondence — AES is the appropriate standard and is produced by the main commercial e-signature platforms.

For HMRC client authorisation (replacing the paper 64-8 or equivalent agent authority forms), HMRC requires at minimum an AES from 6 April 2025. This was a significant change — prior to this date, HMRC required wet ink signatures on agent authorisation forms.

The main e-signature platforms for UK accounting practices

DocuSign

DocuSign is the market-leading e-signature platform globally. For accounting practices:

  • Produces AES-standard signatures on all documents
  • Integrates with practice management platforms (Karbon, TaxDome, Iris) and general business software
  • Envelope-based pricing (you pay per document sent for signature)
  • Strong audit trail: IP address, timestamp, authentication method, and document hash recorded for each signature
  • Available to all signatories without requiring them to have a DocuSign account

DocuSign's envelope pricing can become expensive for high-volume practices sending many engagement letters each month. Compare the per-envelope cost against your expected monthly volume carefully.

Adobe Acrobat Sign

Adobe Acrobat Sign is DocuSign's main competitor. For practices already on Adobe Creative Cloud or Adobe Document Cloud, Acrobat Sign is included or available as an add-on at a lower marginal cost than DocuSign.

  • Produces AES-standard signatures
  • Native integration within Adobe Acrobat, which is widely used for PDF work in accounting
  • Integrations with Microsoft 365, Salesforce, and other business platforms
  • Audit trail comparable to DocuSign

Glide

Glide is a UK-developed e-signature and client portal platform built specifically for accounting and professional services practices. Key differentiators:

  • Designed around accounting firm workflows: engagement letters, accounts approval, tax return sign-off, payment collection
  • Produces AES-standard signatures
  • Branded client portal included — clients sign within the firm's branded interface, not a generic DocuSign/Adobe interface
  • Flat monthly pricing rather than per-envelope, which may be more cost-effective for high-volume practices
  • HMRC-compliant for agent authorisation (AES standard confirmed)

Glide is particularly popular among smaller to mid-size UK accounting practices for its focus, pricing model, and UK-specific design.

Signable

Signable is a UK-based e-signature platform with a focus on small and medium businesses. It produces AES-standard signatures, is GDPR-compliant with UK data processing, and offers competitive pricing for lower-volume use cases.

Practice management integrations

Several practice management platforms include e-signature as part of the package:

  • TaxDome: built-in e-signature within the client portal; AES-compliant
  • Karbon: integrates with DocuSign and Signable; native e-signature feature in development
  • Iris Practice Management: includes Iris SmartSign for e-signature within the platform

Using e-signature within your practice management platform reduces the number of separate tools and keeps all document status visible in one place.

HMRC requirements for agent authorisation

From 6 April 2025, HMRC accepts Advanced Electronic Signatures for agent authorisation forms submitted via its digital agent services. This enables the following workflow to be entirely paperless:

  1. Draft the agent authorisation request within your tax software or practice management system
  2. Send to the client for review via your client portal
  3. Client signs using an AES-compliant e-signature within the portal
  4. Signed authorisation is submitted to HMRC digitally

Before implementing this workflow, confirm with your e-signature provider that their platform meets HMRC's specific AES requirements. Some providers have published explicit confirmation of HMRC compliance; others have not. If you are uncertain, contact HMRC's agent helpline or check the latest agent guidance on GOV.UK.

Note: the AES acceptance applies to agent authorisation. Other HMRC-specific forms may have different requirements — check the relevant guidance for each document type before assuming all HMRC forms accept e-signatures. For a broader view of technology tools for accounting firms, visit the AI tools and technology for UK accountants hub.

Implementing e-signature in your practice

Start with engagement letters: engagement letters are the lowest-risk document to pilot e-signature with — they are standard documents, clients expect to sign them, and the professional and legal requirements are clear. A successful engagement letter pilot builds confidence before extending to accounts approval and HMRC authorisation.

Choose a platform that integrates with your workflow: a standalone e-signature tool that requires manually uploading documents and downloading signed copies creates its own administrative overhead. Choose a platform that integrates with your practice management system or client portal so document sending and signing is part of the workflow, not a separate step outside it.

Prepare a client-facing one-pager: many clients will not have signed a document electronically before. A brief guide explaining how it works, why it is secure, and what they need to do to sign reduces confusion and failed signing attempts.

Retain the audit trail: the signed document and the associated audit trail (IP address, timestamp, authentication method) should be retained in your client file as evidence of the signed agreement. Most platforms provide an automatically generated audit certificate alongside the signed document.

E-signatures produced by major commercial platforms at AES standard are legally valid for most commercial documents in the UK under the Electronic Communications Act 2000 and retained eIDAS provisions. They have the same legal standing as a wet ink signature for the vast majority of documents accounting practices use.

The main exceptions are documents that require witnessing, documents required to be in deed form, and certain statutory forms that specify the signature method. Engagement letters, accounts approval letters, and most practice correspondence are not in these categories.

Key takeaways

  • Advanced Electronic Signature (AES) standard is the appropriate tier for accounting practice documents and is produced by all major commercial e-signature platforms (DocuSign, Adobe Acrobat Sign, Glide, Signable).
  • HMRC accepted AES for agent authorisation from 6 April 2025, enabling fully digital client authorisation workflows for tax work.
  • Glide is a UK-developed platform built specifically for accounting firms with flat-rate pricing and a branded client portal; DocuSign and Adobe Acrobat Sign are the leading global platforms with broader integrations.
  • Start with engagement letters as the lowest-risk pilot before extending e-signature to accounts approval and HMRC authorisation.
  • Retain the signed document and the provider's audit trail certificate in your client file as evidence of valid execution.

Frequently asked questions

Yes. E-signatures at AES standard are legally valid for engagement letters under the Electronic Communications Act 2000 and retained UK eIDAS provisions. They have the same enforceability as wet ink signatures for commercial contracts of this type. The key requirement is that the e-signature platform produces a proper AES, including an audit trail recording the signatory's identity, the timestamp, and the document integrity hash.

Does HMRC accept e-signatures on 64-8 agent authorisation forms?

HMRC changed its position on 6 April 2025, and now accepts AES-standard e-signatures for agent authorisation submitted via its digital services. The e-signature must meet the AES standard. Check current HMRC agent authorisation guidance on GOV.UK for the latest requirements, as the process for submitting digitally signed authorisations may differ from the process for paper forms.

How do clients sign documents without creating an account?

All major e-signature platforms allow signatories to sign without creating an account. The client receives a link via email, opens the document, and signs by typing their name, drawing a signature, or using another authentication method — without needing to register. The platform tracks the authentication and creates the audit trail behind the scenes.

What happens if a client signs in the wrong place or makes a signing error?

Most e-signature platforms allow documents to be voided and re-sent if the client makes an error. The void record is retained in the audit trail, and the replacement document creates a fresh signing event. In practice, well-designed signing documents with clear field placement and instructions minimise signing errors.

Is e-signature cheaper than printing and posting documents?

Yes, for most practices. Per-document costs for printing (paper, ink, envelope, postage) and the staff time for printing and handling are typically higher than e-signature platform costs per document, particularly when the reduced chasing time is included. Flat-rate platforms (Glide) are particularly cost-effective for high-volume practices. The business case for e-signature is strong when total process cost (including staff time) is included, not just platform licensing.