Final fiscalisation UI showing plan selection, checkout, and subscription management
Case Study
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Sumup
Role
Senior Product Designer
Timeline
2020-2021
Team
Cross-functional (2 Teams)
Designing the First Subscription Product on a New Revenue Platform
In 2020, SumUp was transforming from transaction fees to recurring revenue. I designed the first product on their new subscription platform, proving the infrastructure could work for 4 million merchants.
01
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Impact
0.0
0.0
Usability Tests Score
Validated self-service subscription flows for regulated products
0
0
+
Future Products Enabled
Foundation product patterns reused for 5 more subscription services.
02
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The Challenge
Proving a New Subscription Platform in Production
SumUp had built a new Billing & Subscription platform to support recurring revenue. Fiscalisation was the first real-world test. The challenge wasn't just designing a tax compliance subscription, it was proving the whole platform actually worked.
"Fiscalisation was the first real-world test of this entire infrastructure."
Key Constraints
German tax compliance requirements (TSE certification)
New technical platform with untested integration points
Two separate teams: Billing API + Product team
Self-service only: support tickets don't scale for 4M merchants
Patterns must scale to 5+ future subscriptions
03
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Process
Respecting Complexity
The subscription service sat between two teams: Billing API and Product. I ran workshops with both, mapping technical constraints with PMs and engineers, then turned all of that into one coherent experience.
The core insight: merchants don't need less complexity—they need complexity revealed progressively, with clear value at each step.
Screen flows and interactions mapped.
This coordination work revealed key decisions
Subscription management lives separately from individual products . I validated this with UX testing
Checkout stays in-product to keep the experience coherent
Billing details widget integrated, but feeling native
Progressive disclosure for complex tax requirements
04
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structure
Designing for Independent Review
Two technical teams, multiple PMs, stakeholders across time zones — I needed a system people could review without me in the room. I built a Figma template where each journey step showed its variations, design rationale, and open questions.
User journey ran top-to-bottom, variations left-to-right. Developers could trace flows on their own. PMs could review async. And by keeping research questions visible, I was showing uncertainty instead of hiding it.
Each journey step documented its rationale and open research questions
05
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Validation
Ensuring Quality Before Launch
I worked with a user researcher to test the core flows with real merchants. All six participants completed checkout without help — confirming our information architecture, payment flow, and subscription management all made sense.
8.5
/ 10
Usability Score
"I think it's good. Simple and uncomplicated."
— Happy SumUp user
One area needed iteration: the technical tax terminology confused some users during testing. We added educational content explaining when fiscalisation applied, addressing the confusion before launch.
06
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Execution
Delivery done, uptake successful
The real test? Fiscalisation went live and just... worked. Day one, minimal support tickets. The design did its job without drawing attention to itself.
Better still: the patterns we built: checkout, subscription management, billing integration that became the template for five more subscription products.
"We went through the entire process of exploring and defining the problem space, competitor research, creating prototypes, validating designs with users and seeing them go live. Strong sense of ownership, critical thinking and attention to detail."
— Steffen Jannsen
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