System designHardsd-g118

Subject SettlementLevel Senior–Staff~50 minCommon in Distributed systems interviewsIndustries Technology

Question

Design the merchant settlement/payout system for a payments platform serving 500K merchants. Each day it must net each merchant's captured payments minus refunds, fees, chargebacks, and reserves, then initiate ACH/SEPA payouts on the merchant's schedule (daily, weekly, on-demand). Payouts go out in bank cutoff windows. Describe how a payout amount is computed correctly and immutably, how you guarantee a settlement batch is sent to the bank exactly once, and how you handle a payout that the bank later returns/fails.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.