# Introducing Session ID to StartPaymentSession — Shopify developer changelog --- ## Introducing Session ID to StartPaymentSession As of Payments Apps API version 2024-10, the StartPaymentSession payload for all payment extension types will have one new field: [session_id](https://shopify.dev/docs/apps/build/payments/request-reference#request-body). This identifier is shared across payment sessions that belong to the same payment group, buyer session, and share payment details. It can be used to power auth rate calculations. *Published: October 01, 2024* Tags: API, New Link: https://shopify.dev/changelog/introducing-session-id-to-startpaymentsession ---