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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 potential to drive virality around Monzo.
This led to Billsback, a new proposition that reimbursed customer bills, turning routine payments into moments of reward and advocacy while encouraging better bill management. It became one of the most successful subscription feature launches of the year.
I led design end-to-end, partnering closely with product, engineering and marketing from early concept through post-launch iteration.
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Framing the bet
To evaluate how reward-led ideas could drive subscription growth at scale, we aligned around a set of principles:
Virality & sharebility: the reward needed a compelling hook that motivated customers to talk about it.
Storytelling & distinctiveness: the experience had to feel emotionally resonant and recognisably Monzo.
Value & practical utility: participation needed to deliver tangible value, not novelty alone.
Clarity & ease of understanding: the structure had to be simple enough to be immediately understood and trusted.
Using these principles, we prioritised five concepts and tested them with customers, assessing willingness to participate, perceived value and likelihood to share.
Two concepts outperformed the rest: Double Payday (rewarding customers with double their salary) and Billsback. While both showed strong participation intent and social shareability, Billsback was prioritised first due to its alignment with our strategic focus on bills and its ability to better validate the viral growth hypothesis.
Designing the entry journey
With subscriber acquisition as the primary goal, the sign-up journey needed to act as a clear Billsback 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 however, financial compliance raised concerns about combining a reward mechanic and a subscription upsell on a single screen.
Rather than treating this as a limitation, I reframed the problem: could separating these moments actually improve clarity and conversion? I aligned the team around two hypotheses:
Giving Billsback a more dedicated moment could better communicate its value and reduce cognitive load.
Retaining plan selection as a distinct step could unlock incremental value by surfacing higher-tier plans.
We iterated on the core flow by introducing a dynamic header that carried the Billsback narrative across steps, preserving intent while leveraging subscription patterns we already knew performed well.
User testing showed a clear preference for this approach, and 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 compared to a sole focus on the lowest tier.
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 to reinforce clarity and trust. As engineering scoping progressed, it became clear this would introduce significant complexity, increase delivery risk and delay launch.
Rather than optimising for data fidelity at the expense of speed, we de-scoped live bill tracking from the initial release. Instead, we focused on making eligibility explicit: clearly communicating which bill types were included and encouraging customers to bring more of their bills into Monzo.
This trade-off allowed us to ship on time, validate the core proposition and avoid the risk of undermining trust through partial or fragile data. Live bill tracking was positioned as a post-launch investment, with early customer feedback confirming it as a clear next priority.
While live bill tracking was de-scoped from v1, the experience was designed to anticipate its introduction - some screens shown reflect this forward-looking state, currently in build at the point of writing.
The virality loop
Virality was intentionally designed into the experience, starting with making winning unmissable. Customers were proactively notified via push notification and a full-screen in-app interstitial, designed to feel celebratory and surprising. Language and tone focused on emotional payoff, reinforcing that customers were genuinely getting value back.
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 that attention into growth, we also introduced a lightweight sharing mechanic within Billsback, allowing customers to invite others to join Monzo or subscribe to access the feature themselves. This created a clear path from delight to advocacy.
Learning from launch
Billsback exceeded new subscriber acquisition targets and generated high levels of organic conversation across social and community channels.
Post-launch, I led a performance deep-dive against our goals, synthesising insights from multiple signals - including a qualitative review of 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. We also identified an opportunity to better educate customers on the broader value of managing bills in Monzo.
These insights surfaced clear growth opportunities: using bills-related moments to prompt Billsback engagement and nudging customers to bring more bills into Monzo from connected accounts. They directly shaped the next phase of work, including contextual nudges tied to bills paid from connected accounts, live bill tracking and moments of new bill celebration.
Outcome and reflection
Billsback validated a new model for subscription-led growth at Monzo - one where emotional payoff, virality and core money behaviours reinforced each other.
By making deliberate trade-offs around scope and sequencing - what to ship now, what to defer and what not to build, we moved quickly without over-investing ahead of evidence. Post-launch learning shaped a clear, evidence-led roadmap, influencing where the organisation invested next and 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.
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