Payment Processing SME

part time (3 Days per Week) | London City

About the Role

Our client, a leading professional institution, is undertaking a large scale payment processing platform migration. We're seeking an expert Payment Processing SME to provide technical and operational expertise throughout this business critical transformation on a part time basis (3 days per week).

This role requires deep technical knowledge of payment processing systems and the ability to bridge between business requirements, technical implementation, and scheme compliance requirements.

Key Responsibilities:

• Act as the primary payments processing specialist, with ownership across authorisation, clearing and settlement, dispute and chargeback handling, fraud prevention controls, and card scheme regulatory standards
• Gather, shape, and confirm end-to-end processing requirements in partnership with programme and workstream stakeholders
• Collaborate closely with internal engineering teams and external processor partners to define technical delivery needs and implementation approaches
• Drive detailed platform migration mapping activities, including BIN structures, product setup, configuration models, and reporting frameworks
• Liaise with processor technical teams to ensure business and operational requirements are accurately reflected in system design
• Provide subject matter expertise throughout all testing phases, including system integration testing, user acceptance testing, and go-live readiness
• Support migration cutover activities and provide hands-on input during post-implementation stabilisation
• Produce and maintain detailed documentation covering processing workflows, configuration standards, and technical design artefacts

Essential Requirements

* Extensive experience in payment processing operations and technology

* Deep technical knowledge of authorisation, clearing, and settlement processes for payment schemes

* Strong understanding of fraud controls, disputes, and chargebacks processing

* Previous involvement in processor migration projects or platform implementations

* Technical proficiency in understanding BIN configurations, product setups, and processor technical architecture

* Ability to work effectively with both business stakeholders and technical engineering teams

* Experience supporting testing cycles for payment systems

Desirable Skills

* Hands-on experience with major processor platforms (FIS, Fiserv, ACI, GPS, Compass Plus, etc.)

* Knowledge of ISO 8583 message formats and payment processing protocols

* Experience with cutover planning and execution for payment processing migrations

* Background in financial services operations or issuer processing

Working Arrangements:

* part time: 3 days per week

* Initially higher on-site presence required during project ramp-up (London City location)

* Flexibility to work more remotely as project matures

* Long-term engagement