AWS Lambda's INIT billing update: What's changing and why it matters for your cloud costs
Starting on Aug. 1, 2025, AWS will bill for the initialization (INIT) phase of Lambda functions, bringing a key change to how you are charged for serverless workloads. This billing update will impact functions using managed runtimes with ZIP archive packaging, which previously excluded the INIT phase from the billed duration. For teams that rely heavily on AWS Lambda, this is a small but significant change. The INIT phase, while short, could introduce costs that were previously invisible.