Interest & Product Logic Specialist

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