Email marketing consistently produces the highest return on investment of any digital marketing channel in professional services. The reason is structural: you own the list, the audience has opted in, the delivery is direct, and the cost per send is close to zero at small volumes. For accounting firms, email is also the most retention-positive channel — it maintains the relationship between engagements and reduces the risk that clients quietly move to a competitor.
The common objection is that accounting clients do not want to be emailed. In practice, clients who are not emailed feel ignored. Clients who receive useful, relevant emails at an appropriate frequency feel valued.
What "highest ROI" actually means
The claim that email has the highest ROI in marketing is cited widely across the industry. Specific figures vary by study and methodology — verify current data with sources like Litmus, the DMA UK, or HubSpot research. What the data consistently shows is that:
- Email reaches an opted-in audience with a pre-existing relationship
- Open and click rates for professional services newsletters significantly exceed those of consumer marketing
- The cost per send on a list of under 2,000 subscribers is effectively zero on free or low-cost tools
- A single well-timed email can generate a direct enquiry, a referral conversation, or a service upsell at near-zero marginal cost
Compare this to paid search (cost per click multiplied by a conversion rate) or social media (falling organic reach that requires paid promotion to maintain), and email consistently wins on cost efficiency for an established list.
The three ways email generates return for accounting firms
1. Client retention
The average accounting client does not change accountants because they found someone better; they change because they forgot why the current firm was good. A monthly newsletter that reminds clients of your expertise, shares useful advice, and surfaces new services keeps the relationship active between the work engagements that might be only annual.
Firms that maintain regular email contact with clients have lower churn rates than those that only email around deadlines. The cost of retaining a client — near zero with a maintained newsletter — is a fraction of the cost of acquiring a replacement.
2. Upsell and cross-sell
An existing client who does not know you offer payroll services, R&D tax advice, or pension planning through a partner will not buy them. A newsletter that mentions a relevant service at the right moment ("we have been helping a number of clients with their R&D claims this year — if your business does any product development, it may be worth a conversation") produces warm conversations that convert at very high rates.
Every service your firm offers that a client does not currently use is a potential upsell, and email is the most natural and non-pushy way to surface it.
3. Referral activation
Clients who receive your newsletter are reminded of you and of your expertise regularly. When a conversation in their network produces "we're looking for a new accountant", the client who read your newsletter last week is significantly more likely to mention your name than one who has not heard from you in six months.
Email is invisible referral marketing. It does not ask for referrals directly; it maintains the top-of-mind presence that makes referrals more likely.
The minimum viable email marketing programme
Three things:
- A monthly newsletter — practical, useful, short, consistent. See the email newsletter article for format guidance.
- A subscriber list — existing clients (with GDPR-compliant consent), warm prospects who have opted in, and professional contacts who want to receive it.
- A tool — Mailchimp, Kit, or ActiveCampaign. The free tiers of Mailchimp and Kit handle lists of up to 1,000 subscribers at no cost.
This is a four-to-six hour monthly investment that produces returns in client retention, referral frequency, and upsell conversion that exceed the equivalent time spent on any other marketing channel.
Key takeaways
- Email produces the highest ROI in professional services marketing because you own the list, the audience has opted in, and the cost per send is near zero.
- For accounting firms, email drives returns through client retention, service upsell, and referral activation.
- A monthly newsletter to clients and warm prospects is the minimum viable programme.
- Verify current ROI benchmarks with sources like Litmus, the DMA UK, or your own email tool's analytics.
- Firms that email clients regularly have lower churn rates than firms that only communicate around deadlines.
Frequently asked questions
How do I get started with email marketing if we have no list?
Start with existing clients — add them to the list with appropriate consent (for B2B marketing to business clients, legitimate interest is usually sufficient; add an unsubscribe option). Add a newsletter sign-up to your website and email signature. The list grows from zero to useful within six to twelve months.
Is UK GDPR a barrier to email marketing?
No, if you follow the rules. For existing B2B clients, legitimate interest is a valid basis for direct marketing emails, provided you offer an easy unsubscribe and your privacy policy is up to date. For new contacts, consent is required. The ICO has clear guidance on email marketing compliance.
How often is too often for client emails?
Monthly is the standard for accounting firms. More than bi-weekly tips the relationship from useful to intrusive for a professional services audience. Less than quarterly risks being forgotten between the emails.
What is a realistic open rate for an accounting firm newsletter?
Open rates for accounting firm newsletters to warm lists of clients and professional contacts typically exceed industry averages because the relationship is stronger. Check current benchmarks with your email tool's analytics — industry averages change and vary by tool.
Should we track open rates and click rates?
Yes. Open rate tells you whether your subject lines are compelling. Click rate tells you whether the content is engaging enough for people to want more. Track both monthly and use them to improve the subject lines and content mix over time.
For more on the email marketing hub, explore our full library of guides for accounting firms.