Open banking overlay on NamPost rails: lessons from year one

Open banking is a trust project with technical dependencies. Year one on NamPost overlay modules (P1-OB-*) showed wins where teams focused on consent UX, stable AIS payloads, and never using external balances to infer grant eligibility (UC-05, X-02).

Lessons

Standards reduce friction. Shared error codes and scope enums speed TPP onboarding.

Consent is product. Step-by-step flows beat legal wall-of-text—Elizabeth stokvel scenario.

Reliability beats catalogue size. Few stable endpoints outperform flaky breadth.

Sandbox-first saves time. Synthetic external bank seed JSON + NamPost SmartCard separation clarifies architecture early.

NamPost-specific rule

Grant APIs ignore external AIS. UI must block “link bank to prove pension eligibility” patterns—regulator export should show firewall tests passing.

Year two priorities

• Revoke SLA ≤60s measurement in Observation Deck.
• Field allowlist integration tests in INT suite.
• Merchant + stokvel reference apps using persona picker.

Year one proved progress is possible with discipline—not hype.