How Alibaba Travel Billing System Achieves 100% Accuracy and Real‑Time Reconciliation

Background

After less than a year of taking over the billing system, the author shares insights on billing system architecture design.

Ubiquitous Billing

Everyday examples illustrate reconciliation, showing how payment confirmations, receipts, and actual assets must align.

Types of Reconciliation

Account‑Asset reconciliation

Account‑Document reconciliation

Account‑Account reconciliation

Billing System Design

The billing settlement core connects upstream services (flights, hotels, cars, trains, compensation) with downstream services (payment, finance, invoicing). The system includes stages such as order collection, billing, accounting, posting, payment, and reconciliation.

Key components:

Order collection: listening to supply‑chain order messages.

Billing: splitting fees into granular items (reservation, refund, change, insurance, service fee, compensation, etc.).

Accounting: merging billing details according to business rules.

Posting: verifying data consistency and intercepting posting errors.

Payment: allowing enterprises to customize billing issuance.

Reconciliation & repayment: enterprises verify details and make repayments.

Reconciliation Design

Three reconciliation methods are used: one‑way, two‑way, and multi‑way, with multi‑way preferred for comprehensive issue detection.

Granularity includes total‑level reconciliation and detailed reconciliation; the recommended approach is to start with total‑level checks and then drill down to detailed analysis.

Reconciliation models cover common business rules, multi‑party comparisons, and billing‑specific rules, aiming to modularize logic and reduce duplicate development.

System Design Key Points

Challenges

Bill accuracy issues caused by upstream message loss, data delays, or incomplete fee data.

Bill detail data not synchronized after changes (e.g., hotel order status), leading to stale offline fields.

Enterprise‑specific customization results in redundant fields.

Full‑Link Monitoring

MAC monitoring for flight billing, posting failures, and amount verification.

PCB monitoring for real‑time order, transaction, and expense data.

T+1 comparison of upstream orders and billing collection tables to trigger compensation and automatic retries.

Offline and issuance data checks to ensure 100% accuracy.

Expression Engine for Billing Data

A configurable expression engine validates and dynamically updates billing fields, enabling custom validation rules such as intercepting empty posting times or zero settlement amounts.

Custom Billing

Enterprises can define custom table headers, field order, and styles, avoiding redundant data presentation and meeting specific business needs.

Next‑Generation Billing System

After more than six months of reconstruction, the system now achieves a 100% one‑time issuance rate and 100% bill accuracy, with a steady decline in ticket volume.

Future plans include building industry‑unique invoice‑bill matching capabilities and enhancing bill usability for customers.