Expense to Payroll Events

Summary

Payroll subscribes to all three Expense lifecycle contracts and maintains a payroll-owned approved-expense projection. It never reads the Expense store during calculation.

Projection behavior

Expense contract	Payroll projection result
ExpenseApprovedEvent	Creates or updates the claim projection as Approved
ExpenseRejectedEvent	Updates the claim projection as Rejected
ExpensePaidEvent	Updates the claim projection as Paid

Only Approved projections for the calculation period contribute to reimbursement totals. Rejected and Paid projections remain as records but are excluded from approved reimbursement calculation.

Payroll ignores duplicate event identities. For the same projected claim, an event older than the projection's last occurrence is ignored. Processing errors are negatively acknowledged and requeued.

Frozen-period behavior

The consumer continues to maintain its projection independently of payroll-run state. A frozen run cannot be recalculated, so later projection changes do not rewrite that frozen run through this consumer. Their effect on a future calculation depends on the run being eligible for calculation.

Requires confirmation

Projection reconciliation, late-event operational handling, frozen-period business policy, and ownership of corrections require confirmation.

Source References

• microservices/src/payroll-service/Messaging/PayrollReadModelConsumer.cs
• microservices/src/payroll-service/Domain/PayrollEntities.cs
• microservices/src/payroll-service/Application/PayrollCalculationService.cs
• microservices/scripts/smoke-payroll.ps1

Related Articles

• Expense events documentation
• Expense technical documentation
• Expense database documentation

See Also

• Expense API documentation
• Expense module

Keywords

• Expense events
• Payroll Events
• Integration contracts

Revision Information

• Status: Draft
• Last reviewed: 2026-07-16
• Review cycle: Quarterly