Interim Finance Manager | AI SaaS Scale-Up

Interim Finance Manager | AI SaaS Scale-Up | London

Harmonic are delighted to be partnering with a founder-led AI SaaS business in their search for an Interim Finance Manager. The business built its own AI platform which it sells to UK service businesses. It launched at the start of 2026 and has grown to c.£1m in annual revenue and a team of eight in its first year. It is funded by its founder, a second-time operator who has an excellent track record of scaling technology businesses. It now needs someone embedded in the business to run the finance day to day.

The Role

This is a full-time interim engagement taking over from the current finance lead, with a handover in early December. Reporting to the founder, the Interim Finance Manager will run the core finance operation for the trading business: management accounts, payroll, AP/AR, VAT and reconciliations, plus the financial admin that comes with a growing business. There is no team underneath this role, so it is fully hands-on. The focus is a strong, reliable finance function, with senior oversight of the wider picture provided separately.

Key Responsibilities

• Produce monthly management accounts
• Run payroll, invoicing, supplier payments and credit control
• Prepare and submit VAT returns
• Complete bank and balance sheet reconciliations
• Handle contracts, paperwork and office-related financial admin
• Pick up finance work across the founder's related entities where needed

Essential Experience

• Part qualified, finalist or qualified (CIMA, ACCA or ACA)
• Finance Manager, management accountant or senior accountant experience in a start-up or scale-up
• Experience in an online or digital business; SaaS or recurring revenue
• Fully hands-on and comfortable running finance on your own

Desirable Experience

• Experience working directly with a founder
• Previous experience in interim or contract roles

Package

Day Rate: £350-450 per day, depending on experience (IR35 status to be confirmed)

Location: London

Contract: 6 months

Start Date: ASAP, with handover before early December

At Harmonic, we are dedicated to fostering an inclusive and equitable workplace. We actively welcome applications from individuals of all backgrounds and assure you that every candidate will be thoughtfully considered for the roles we represent, without regard to race, religion, gender expression, disability, or sexual orientation.