Enter password to view
Monzo Billsback
Shaping a new subscriptions growth engine by reimagining the monthly bills experience
My role
Product Design Lead
Company
Monzo
Year
2025
Overview
As part of Monzo’s subscription strategy, we identified an opportunity to turn monthly bills into a surprise-and-delight growth engine with viral potential.
This led to Billsback - a proposition that reimbursed customer bills, turning routine payments into moments of reward and advocacy. It became one of the Monzo's most successful subscription launches.
I led design end-to-end, working with product, engineering and marketing from concept through post-launch iteration - including using AI tools to build and ship code changes directly to production.
1422%
Framing the bet
To evaluate how reward-led ideas could drive subscription growth, we used four lenses: virality, distinctiveness, practical value and clarity.
Using these lenses, we prioritised five concepts from ideation workshops and tested them with customers - assessing whether they were compelling enough to talk about, valuable enough to participate in and simple to understand.
Two concepts outperformed the rest - Double Payday and Bill Back. Bill Back, which became Billsback, was prioritised first due to its strategic fit and ability to better validate the viral growth hypothesis.
Mapping the opportunity space
Once Billsback was prioritised, the next challenge was turning a broad growth proposition into a focused first release.
I mapped the end-to-end customer journey, using user flows to define key interaction paths - from discovery and sign-up through to moving bills into Monzo and tracking progress. This exposed where the experience needed to work hardest, particularly around education, trust and moving customers from interest to action.
I then explored the experience at low fidelity, creating a shared artefact to critique before committing to detailed UI. Team reviews helped us identify what was working, what felt unclear and where the proposition risked becoming too complex.
This shaped a focused first release that could validate the core growth hypothesis, while setting out a roadmap of wider opportunities.
Designing the entry journey
With subscriber acquisition as the primary goal, the sign-up journey needed to act as a clear hook while guiding customers into the subscription funnel.
Monzo already had a proven two-step subscription upsell centred on the lowest-tier plan. Early in design, financial compliance raised concerns about combining a reward mechanic and subscription upsell on one screen.
Rather than treating this as a limitation, I reframed the problem - could separating these moments improve clarity and conversion? I aligned the team around two hypotheses - that a dedicated Billsback moment would better communicate value, while a distinct plan-selection step, with a dynamic Billsback headline, could surface higher-tier plans.
User testing showed a clear preference for this approach. The final flow delivered one of the strongest conversion rates across all subscription funnels, validating the decision to trade a shorter flow for clarity and intentional sequencing. We also saw 36% of sign-ups via higher-tier plans, increasing ARPU.
Designing for trust under constraint
Post sign-up, Billsback needed to give customers confidence that it was working - particularly around which bills were eligible and entered into each monthly draw.
Early concepts explored surfacing live bill data during sign-up and within the feature. As engineering scoping progressed, it became clear this would add significant complexity and delay launch. Rather than optimise for data fidelity at the expense of speed, we de-scoped live bill tracking from the first release and focused on making eligibility explicit by clearly communicating which bill types were included.
This allowed us to ship on time and validate the core proposition. Live bill tracking was then prioritised as a post-launch iteration and has since been released, with early metrics already positive.
The update was subsequently released as a post-launch iteration, driving a 23% uplift in paid conversion.
By giving customers a clearer path to move more bills into Monzo - through simple steps, guidance and shortcuts, all tied directly to the Billsback value proposition - we also increased the number of bills paid from Monzo.
This encouraged better money behaviours by connecting bills in Monzo with tools that support budgeting, such as Bills Pots and the bills calendar, while also increasing deposits into Monzo.
The virality loop
Virality was intentionally designed into the experience, starting with making winning unmissable. Customers were notified via push notification and a full-screen in-app interstitial, designed to feel celebratory and surprising.
This moment drove significant organic sharing. Customers talked publicly about their wins, compared Monzo favourably to other banks and shared screenshots - creating social proof that money-back rewards from a bank felt unexpected and meaningful.
To convert attention into growth, we introduced a lightweight sharing mechanic within Billsback, allowing customers to invite others to join Monzo or subscribe themselves. This created a clear path from delight to advocacy.
Shipping direct to code with AI
Beyond the core release, I used AI tooling to take smaller Billsback improvements from design through to production code.
Using Cursor, I connected to GitHub, pulled down the product repo and implemented changes directly in the codebase. One example was a customer-led improvement to add a native share sheet, making it easier for customers to send their Monzo account details via Messages, WhatsApp or email when moving new bills.
I prompted the implementation, tested it on a staging tenancy, raised a pull request, responded to review feedback, then merged and deployed the change. Engineering input was limited to PR review, allowing me to drive feature iterations autonomously within the team’s development workflow.
This changed the speed and shape of iteration. Instead of design ending at handoff, I could close the loop between customer feedback, product design and shipped improvements.
Learning from launch
Billsback exceeded new subscriber targets and generated high levels of organic conversation. Post-launch, I led a performance deep-dive, synthesising multiple signals - including 60+ customer support interactions and analytics across acquisition, funnel performance and bill migration.
The clearest insight was uncertainty: customers wanted greater reassurance that Billsback was working, and confidence that both existing and newly transferred bills were included.
These insights shaped the next phase of work - live bill tracking, contextual nudges tied to bills paid from connected accounts and moments of new bill celebration.
Outcome and reflection
Billsback validated a new model for subscription-led growth at Monzo - one where customer delight, virality and core money behaviours reinforced each other.
By making deliberate trade-offs around scope and sequencing, we moved quickly without over-investing ahead of evidence. Post-launch learning shaped a clear roadmap, leading subscription leadership to prioritise scaling Billsback further.
Billsback evolved from a successful launch feature into a long-term growth surface, increasing confidence in reward-led experimentation and shaping how future subscription bets are framed and evaluated.