Vegalabs AS, a Norwegian startup, owes $17,600 to Microsoft for using Anthropic’s Claude models on Azure — despite holding $25,060 in active Azure for Startups credits. The bill accrued because Anthropic’s Claude deployments via Azure Marketplace fall outside Microsoft’s sponsorship coverage, even though they appear in the same portal and deployment flow. Vegalabs says it deleted the Claude instance within an hour of spotting the charges, but not before $21,168 in unused credits expired on September 8. Its card issuer blocked Microsoft’s attempted $16,500 charge over suspected fraud. The startup now has a $17,600 invoice, no credits left, and no resolution after seven support exchanges. Four of them AI-generated, two from Anthropic, five from Microsoft. Both companies declined to waive or refund the amount. Microsoft told Vegalabs its Marketplace charges are handled by Anthropic. Anthropic told Vegalabs Microsoft controls the refund. Neither corrected the AI responses that mislabeled Vegalabs’ account as an ‘Azure Student Sponsorship’. Microsoft’s own Claude deployment guide warns that credit-only subscriptions aren’t supported, but the Azure portal showed available credits while Marketplace charges mounted silently. Vegalabs admits it didn’t read the exclusions or set a budget alert. It disputes neither the usage nor the rule. Only the lack of in-context warnings during deployment. Microsoft confirmed receipt of The Register’s inquiry on October 6 but offered no statement. Anthropic did not respond. The case mirrors a March 2026 incident where third-party model charges bypassed Azure sponsorship credits, suggesting the billing boundary between Microsoft’s infrastructure and its Marketplace partners remains operationally opaque. Developers deploying Claude, or any third-party LLM via Azure Marketplace, should assume sponsorship credits won’t apply. And verify billing configuration before provisioning. Microsoft says it’s reviewing ‘customer-facing clarity’ around Marketplace billing. No timeline was given.