We are looking for a specialist who combines financial know-how with strong analytical skills to join our Core Ledger team. Our platform contain core ledger systems both fully developed internaly and developed and delivered by external suppliers. As an Interest & Product Logic Specialist, you will define and document the business rules behind interest, fees, and product configurations, and verify and test that what our internal- and external suppliers deliver matches our requirements and works correctly. A significant part of this role is providing hands-on internal support to colleagues across the business who have questions about interest, fees, and product behaviour — this is something all specialists in the team spend a lot of time on. Getting this right is essential — it directly affects how accurate and competitive our financial products are. You will join a small, close-knit team and have a great opportunity to make a direct impact early on and help shape it as it grows.
Key Responsibilities
Define and document detailed requirements for interest calculation logic, accrual rules, and fee structures, to be delivered by external suppliers
Translate financial product requirements from business and product teams into precise specifications for our suppliers
Verify and test the product configuration delivered by suppliers, ensuring it behaves correctly for all financial instruments
Ensure the mathematical and financial correctness of calculation logic delivered, including edge cases and regulatory requirements
Collaborate with finance, compliance, and product teams to validate that supplier deliveries meet business intent
Support audit and regulatory reporting by ensuring calculation logic is transparent, traceable, and well-documented
Investigate and resolve discrepancies in interest calculations, fee postings, or product behaviour, working with suppliers when needed
Define and execute test cases for financial calculation logic, including boundary and regression tests
Provide hands-on internal support to other teams (finance, customer service, operations, and others) on questions about interest, fees, and product behaviour — this is a significant and ongoing part of the role
Qualifications and Experience
Desired Skills
4+ years of experience in a financial, analytical, audit (internal or external), or product role within financial services, lending, or payments
Strong understanding of interest calculation methodologies (e.g. effective interest rate, simple interest, compound interest, XIRR)
Experience writing detailed financial business rules and specifications for systems built by others, , or experience auditing and validating such systems
Solid grasp of product structures in consumer credit, BNPL, or instalment lending
Ability to work with complex financial specifications and verify that delivered systems implement them correctly
Nice to Have
Experience conducting audits, controls, or reviews of financial systems, ideally related to interest or fee calculation
Knowledge of Nordic or European consumer credit regulation (e.g. Consumer Credit Directive)
Experience with configuration-driven financial product frameworks delivered by suppliers
Background in financial audit, actuarial science, quantitative finance, or financial mathematics
Familiarity with accounting principles as they relate to interest and fee recognition
Prior experience in internal audit, external audit (Big Four or other firms), or operational risk control functions
Behaviours
Exceptional analytical rigour — comfortable with mathematical precision and financial logic
Service-minded and approachable — enjoys helping colleagues understand interest, fee, and product logic
Strong bridge-builder between finance/business language and supplier requirements
Thorough documenter — understands that correctness must be explainable and auditable
Curious and proactive in challenging assumptions and validating requirements
Collaborative, with an ability to work effectively with business stakeholders and external suppliers
Education
BSc or MSc in Computer Science, Software Engineering, Finance, Audit, or equivalent practical experience.
Languages
Fluent English is required for this role. Swedish language is a plus.
What We Offer
A key role in building and shaping a modern, cloud-native core ledger platform
A collaborative, cross-functional team environment with short decision paths
Competitive salary and benefits package
Flexible working arrangements with hybrid options
Opportunities for professional development and continuous learning
A chance to make a real impact in the fintech space across the Nordic market
Modern office in central Málaga with a strong team culture