Design Corporate Travel Program - System Design | WinJob

Problem Statement: Corporate Travel & Business Profiles

Corporate travel programs (Uber for Business, Lyft Business, Concur integrations) wrap consumer ride-hail with policy governance, central billing, and finance-grade audit. Employees book under a business profile; the platform must prove which rules applied, bill the organization, and export receiptless expense lines without duplicate submissions.

Concern	Design stance
Policy truth	Versioned `travel_policy` pinned on each `business_trip`
Money path	Central org billing account; platform never commingles personal PAN
Export path	Idempotent Concur batches keyed `org_id:export_date`
Abuse	Rules + graph signals on personal-use leakage

Section focus (sec-001): Uber for Business and Lyft Business sell governed mobility: employees book rides under company-paid profiles while finance receives audit-grade expense lines without manual receipt chasing.

Capacity signal: 2.4M enrolled employees; 180k concurrent policy evaluations/s at Monday 9am peaks

javaOne Dark Pro

1 public record PolicyEvalResult(boolean allowed, int policyVersion, List<String> violationCodes) {}
2 public final class ExpenseLine {
3   private final String tripId;
4   private final String orgId;
5   private final int amountCents;
6   private final String costCenterId;
7 }

pythonOne Dark Pro

1 def export_idempotency_key(org_id: str, export_date: str) -> str:
2     return f"{org_id}:{export_date}"
3  
4 def rolling_budget_spend_cents(lines: list[int], cap: int) -> bool:
5     return sum(lines) <= cap

typescriptOne Dark Pro

1 export interface BusinessTripRequest {
2   employeeId: string;
3   businessProfileId: string;
4   costCenterId: string;
5   draftEstimateCents: number;
6 }

Operational trace (sec-001)

Employee selects Business profile, Policy Engine evaluates max fare and vehicle class before match, trip bills org_id central invoice, nightly Concur export attaches GL code.

On-call metrics: policy_block_rate, expense_export_lag_hours, personal_trip_leakage_pct — treat sustained export lag above SLA or personal-trip leakage above 0.1% as P1 finance incidents.

Interview pivot: If interviewer asks flights/hotels, scope phase-2 TMC connector; MVP is on-demand ground transport with expense export.

Why interviewers care

Corporate Travel Program interviews reward crisp scope, explicit trade-offs, and failure stories—not generic microservice diagrams.

Interview checkpoint

Name one failure story for Problem Statement: Corporate Travel & Business Profiles that proves you understand real outages, not happy-path diagrams.

Key Highlights

•policy_version pin (sec-001)
•Central bill path (1)
•Concur idempotent export (understanding)
•Trip adapter isolation (0)

1	public record PolicyEvalResult(boolean allowed, int policyVersion, List<String> violationCodes) {}
2	public final class ExpenseLine {
3	private final String tripId;
4	private final String orgId;
5	private final int amountCents;
6	private final String costCenterId;
7	}

1	def export_idempotency_key(org_id: str, export_date: str) -> str:
2	return f"{org_id}:{export_date}"
3
4	def rolling_budget_spend_cents(lines: list[int], cap: int) -> bool:
5	return sum(lines) <= cap

1	export interface BusinessTripRequest {
2	employeeId: string;
3	businessProfileId: string;
4	costCenterId: string;
5	draftEstimateCents: number;
6	}

Problem Statement: Corporate Travel & Business Profiles

Operational trace (sec-001)

Why interviewers care

Interview checkpoint

Key Highlights

Section Rescue Kit