Martin Brennan founded Onside Accounting in June 2021 with just a laptop, a handful of early-stage tech clients, and a clear vision to create a “work-from-anywhere” practice. Fast forward four years, and the firm has grown to employ 38 staff, fostering a fully remote culture while serving a diverse client base of high-growth start-ups. In a recent Growth Club session, Brennan and Jordan Vickery shared insights into what strategies worked, what challenges they faced, and how other firms can replicate their success.
Create a Runway Before You Jump
“On day one I had enough money to pay the bills.” – Martin Brennan
One of the first steps Brennan took was negotiating an eight-month, tapering notice period with his previous employer. This strategic move allowed him to use his evenings and weekends to onboard clients from his personal network and build up cash reserves. This financial cushion alleviated the common panic many founders experience in their first quarter. It enabled him to concentrate on securing the right work rather than simply chasing projects that would cover that month’s mortgage.
The key takeaway from this experience is to map out your personal burn rate alongside your business overheads. Then, design an exit strategy that ensures both are funded for at least six months. This preparation will provide essential breathing room as you launch your venture.
Hire for Leverage, Not Headcount
In most firms, the first recruit is often a junior bookkeeper. However, Brennan took a different approach by hiring an Operations Director without an accounting background. The demands of HR, IT, recruitment, employee onboarding, and system migrations were consuming half of his week. This strategic hire doubled his billable capacity and, consequently, his sales capacity almost overnight. As a result, revenue growth in 2023 was the strongest on record.
If a task cannot be invoiced to a client but consumes the owner’s valuable time, consider making a senior non-billable hire early on. This decision can pay dividends in the long run, allowing the firm to focus on its core competencies and drive revenue growth.
Keep the Engine Simple
Onside’s entire technology stack can be summarised succinctly on one slide:
• Workflow: App
• Ledger: Xero
• Payroll: BrightPay
• Payments: Apron
• Practice Management: Karbon
• File Storage: SharePoint
Every new client is migrated within the first month of engagement. Pricing is tied to transaction volumes, with annual reviews to adjust for any scope creep. By standardising tools and pricing based on objective drivers, you can drastically reduce onboarding time, minimise training costs, and eliminate frustrations associated with “special snowflake” requirements.
Make Culture a System, Not a Slogan
Fully remote teams can easily drift unless communication is intentionally structured. Onside has implemented a regular cadence of activities to maintain connection. These include weekly all-firm technical or soft-skills training sessions, monthly company updates featuring KPI dashboards, quarterly one-on-ones linking individual performance goals to company values, and informal coffee chats, known as “donut chats,” pairing staff for casual conversations.
The firm reviews its values with the entire team every six months. These values have evolved since the company’s inception, reflecting the growth and changes within the team. Candidates are expected to provide clear examples of how they care for colleagues, embrace growth, and thrive in a home-working environment during the interview process. If they hesitate when asked for inspiration, they may not be a suitable fit for the culture Onside has cultivated.
Step Back – Then Stay Back
Today, Brennan manages just one client at the request of that client and has appointed a Commercial Director to oversee sales. The true test of his systems came in April 2025 when he took two weeks of paternity leave without engaging in emails or Slack. Upon his return, he found no urgent issues; the systems, not individual heroes, kept the firm operating smoothly.
Documenting hand-offs, empowering managers, and testing the set-up during genuine absences are crucial for ensuring sustainability in operations. This approach allows the firm to operate efficiently without being overly reliant on any one individual, fostering resilience and adaptability in the face of change.
Mistakes Made (So You Don’t Have To)
Throughout their journey, Brennan and Vickery encountered several challenges that serve as valuable lessons for other firms. Rushed hiring processes under pressure led to significant headaches later on, as did accepting clients that were off-niche, which strained systems and negatively impacted morale. Additionally, holding back KPI data slowed the team’s commercial awareness; full transparency proved beneficial in fostering a culture of accountability and engagement.
Signs You’re Scaling, Not Just Growing
Recognising the difference between scaling and merely growing is crucial for sustained success. Signs that your firm is truly scaling include:
• The founder can disappear for a fortnight, and the inbox remains calm.
• Senior leaders have distinct responsibilities; no one is wearing multiple hats.
• Staff reference company values spontaneously in client interactions and Slack conversations.
• Revenue remains stable, even in the event of a major client shutting down.
Bringing It All Together: The Path to Sustainable Scale
Scaling an accounting firm is less about relentless hustle and more about thoughtful design. To achieve sustainable growth, consider the following:
• Design your runway for a smooth transition into entrepreneurship.
• Design your first leverage hire to maximise efficiency.
• Design a tech stack that enables self-training and flexibility.
• Design cultural rituals that can endure through busy periods.
By establishing these foundational elements, as Brennan’s experience illustrates, headcount and profit are likely to take care of themselves. This strategic approach allows your firm to thrive in a competitive landscape, creating a sustainable model for long-term success.
