Your unbilled invoice reconciliation workflow is about to change. Microsoft is retiring the CSP unbilled invoice reconciliation API v1 on March 15, 2026. If your technical team hasn't already migrated to API v2, the clock is ticking.
This isn't a minor update. This is a performance transformation—from 15+ hours to retrieve invoice line items down to just 15 minutes. And if you're still using v1 after March 15, you won't be able to access unbilled invoice details at all.
Let's talk about what's changing and what you need to do.
The deadline: March 15, 2026
On March 15, 2026, API v1 stops working. After that date, it will no longer provide access to unbilled invoice line items for modern commerce transactions. Your team loses access to critical reconciliation data—which means your billing operations stall.
This affects:
- CSP direct bill partners
- CSP indirect providers
- CSP indirect resellers
- Anyone pulling unbilled invoice data via API v1
If you're still on v1 after March 15, you're blocked until you migrate.
Why API v2 matters (and why it's worth the effort)
API v1 was built for smaller datasets. When you're dealing with millions of line items across hundreds of customers, it becomes a bottleneck. Retrieving unbilled invoice data could take more than 15 hours. Your reconciliation processes ran overnight. Your accounting teams waited.
API v2 is asynchronous. It's built for scale. Same job? 15 minutes.
This means:
- Faster reconciliation cycles
- Real-time visibility into unbilled invoices
- Better cash flow forecasting
- Reduced manual follow-up
For partners managing thousands of customers, this is the difference between same-day and next-week financial visibility.
What's changing technically
Microsoft introduced API v2 in September 2025. It's already live. If your technical team hasn't started, now is the time.
Key differences:
API v1 (Retiring)
- Synchronous requests- 15+ hours to retrieve data
- Blocks until complete
- Single-threaded
API v2 (New standard)
- Asynchronous requests- 15 minutes to retrieve data
- Non-blocking execution
- Batch processing optimized
API v2 gives you a request ID and says "check back later." You can continue other work. When it's ready, the data is there.
The migration path: What your technical team needs to do
- Review the API v2 documentation. Microsoft published Get invoice's unbilled reconciliation line items asynchronously API v2 with full details and code samples.
- Test in sandbox. Your development environment should mirror production. Run the new API against test data first.
- Validate the data contract. API v2 returns data in a different format. Make sure your backend systems can parse and consume it correctly.
- Schedule the cutover. You don't need to migrate everything at once. Plan the timeline with your team. But finish before March 15.
- Monitor the transition. Run parallel validation for a period. Ensure API v2 data matches what you expect before fully retiring v1.
Important: Cloud-specific limitations
API v2 is currently available for the public/global cloud only. If you operate in:
- Azure Government
- Azure Germany
- Azure operated by 21Vianet
You'll continue using the existing APIs for now. Those environments aren't being retired yet.
What happens if you don't migrate
After March 15, API v1 requests fail. Your systems can't fetch unbilled invoice line items. Your reconciliation pipeline breaks. You lose the ability to:
- Validate monthly billing accuracy
- Dispute line items
- Reconcile against customer payment records
- Forecast cash flow from modern commerce transactions
This is a hard stop—not a slow sunset. Plan accordingly.
Resources and next steps
- API v2 Documentation – Full technical specs, code samples, and integration patterns
- CSP Technical Training Recordings – Register to watch recordings covering this change in detail
- Partner Community Q&A Call – Ask questions live (upcoming sessions available)
- Other Upcoming API Changes – Check what else is changing in your integration surface
- Partner Center AI Assistant – Use the billing assistant on the Billing overview page, or open a support ticket if you get stuck
Action: Audit your current state
Before your technical team dives into migration, answer these questions:
- Which systems currently use API v1 for unbilled invoice reconciliation?
- How long do current reconciliation jobs take?
- What's the data volume (number of customers, line items per month)?
- Who owns the migration (engineering, finance ops, third-party vendor)?
- When can you test API v2 in sandbox?
Once you answer these, you have a clear picture of migration scope and effort.
TL;DR
- Deadline: March 15, 2026 – API v1 stops working. No more unbilled invoice access via the old endpoint.
- Impact: CSP direct bill partners, providers, and resellers – Anyone pulling unbilled invoice data through API v1
- The gain: 15+ hours → 15 minutes – API v2 is asynchronous and built for millions of line items
- Cloud limitation: Public/global cloud only – Azure Government, Germany, and 21Vianet continue with existing APIs
- Migrate now: Test in sandbox, validate data, plan your cutover before March 15
- Resources: Documentation, training, and support channels are live – Your team has everything needed to migrate successfully
Next steps: Schedule time with your technical team to review API v2 documentation and plan the migration. Don't wait until February to start—March 15 comes faster than you think.