The definition that pulls you in
45 CFR 160.103 treats as a business associate anyone outside a covered entity's workforce who handles PHI for it, whether by creating, receiving, maintaining or transmitting it. The rule names the kind of work that qualifies: claims processing, data analysis, billing, practice management, utilization review and similar functions. That list reads like a description of Bengaluru's health-adjacent outsourcing and product work.
The chain continues downstream. If your client is itself a US vendor, the same definition makes you a subcontractor, and subcontractors that handle PHI are business associates too.

