$17,493 in Undisclosed Marketplace Charges with No Cost Visibility, No Recourse, No Accountability

I'm a co-founder of a 13-person startup in the Microsoft for Startups Founders Hub program. I'm posting here because after two months of support tickets, calls, and emails across both Microsoft and Anthropic, I have been unable to get anyone with decision-making authority to address this issue. I'm hoping this reaches someone at Microsoft who can help, and that other affected founders in the program will share their experiences.

What happened:

In February 2026, we deployed Claude Opus 4.6 and Sonnet 4.6 through Azure AI Foundry as part of a migration of our AI infrastructure. We are active users of our Azure sponsorship credits and assumed, as anyone would, that these models were covered the same way Azure OpenAI models are. There was no indication otherwise during deployment.

In early March, we received our first invoice: $1,078.07 (invoice G144899694, billing period 02/01–02/28). We were shocked, but we paid it immediately and removed all Anthropic model deployments from our account to prevent further charges.

It didn't matter. On April 9, we received a second invoice: $16,414.94 (invoice G151890529, billing period 03/01–03/31). Despite removing the deployments in mid-March, charges had already accumulated for the first half of the month. We are unable to pay this invoice. Our total exposure across both invoices is $17,493.01.

Why we had no way to prevent this:

1. No billing distinction at deployment. Azure AI Foundry presents all models (Microsoft-native and third-party) in the same unified interface. There is no warning, label, or confirmation step indicating that certain models are excluded from sponsorship credits.
2. No cost visibility whatsoever. The Azure AI Foundry monitoring dashboard has an "Estimated Cost" section that is completely blank for these models, with a disclaimer: "Cost monitoring is available for Foundry Models sold directly by Azure only." We could see token counts but had zero visibility into what we were being charged.
3. Token counts that don't explain the charges. The dashboards show our Claude Opus 4.6 deployment used 63.4M tokens and our Sonnet 4.6 deployments used roughly 170M tokens combined. At published rates, that should be in the low thousands, not $17,500. My analysis shows the dashboard hides billions of cached tokens (prompt caching reads and writes) that are invisible in the monitoring UI but account for the vast majority of the bill. There is no view in Azure that provides a breakdown of these charges by token type.
4. No alerts or notifications. There were no cost alerts, no threshold warnings, and no notifications at any point.
5. No indication in any Azure portal that charges were hitting our credit card. There was no line item, no pending charge, no Marketplace spend summary - nothing anywhere in the Azure ecosystem that showed dollars accumulating against our payment method for these deployments.

What happened when we asked for help:

• Azure Support (TrackingID#2603090040002936): After a month-long wait, a support engineer told us Microsoft cannot issue credits for Marketplace charges and directed us to Anthropic. The first version of the response email referenced "Azure DDoS Protection Standard" instead of our actual issue, suggesting the volume of similar cases in the queue.
• Anthropic: Their AI support bot responded within one minute with a blanket statement and closed the ticket four hours later. I escalated, but have still not received a response over a month later.
• Microsoft for Startups Team (TrackingID#2604070040009778): Told us they cannot apply Marketplace charges against sponsorship credits and referred us to a Marketplace billing contact.
• Azure Marketplace billing contact: Pending response.

The pattern is clear: Microsoft directs us to Anthropic. Anthropic directs us to Microsoft. The Microsoft for Startups team directs us to Azure Marketplace billing. No one takes responsibility.

What I'm asking for:

1. A full refund of $17,493.01 across invoices G144899694 and G151890529
2. That Microsoft implement clear billing warnings in Azure AI Foundry before deploying models that are excluded from sponsorship credits.
3. That Microsoft provide actual cost visibility in the monitoring dashboard for all models deployed through AI Foundry, not just first-party models.

To other founders in the program:

If you have experienced this same issue, please reply to this thread. I know I'm not alone because this has been covered by The Register, InfoWorld, and Computerworld, and at least 20 founders have signed a Change.org petition about it. The more founders who come forward with specific amounts and case numbers, the harder this is to ignore.

We joined Microsoft for Startups because the program was supposed to help early-stage companies manage infrastructure costs during the most financially vulnerable period of our growth. Instead, the program's own platform generated charges within 2 weeks that exceed the total sponsorship credits we've consumed over the past year, with no visibility, no warning, and no path to resolution.

With Further Inc. | Microsoft for Startups Founders Hub

Azure Support TrackingID #2603090040002936

Startup Support TrackingID #2604070040009778