Overview

Amazon has added a Boolean attribute named lowCostStore to three core APIs: the Finances API (v0), the FBA Inventory API (v1), and the FBA_INVENTORY_AVAILABILITY_CHANGES notification. The flag appears as soon as a seller enrolls a SKU in the Low‑Cost Store program, which opened for sign‑ups in early 2024. Sellers who depend on API feeds for pricing, stock management, or fee reporting need to incorporate this field to capture the reduced‑fee benefits automatically.

Key Points

• Attribute name — All three endpoints now return a Boolean field called lowCostStore; it is set to true for items that belong to the Low‑Cost Store program.
• Uniform presence — The same flag is included in financial transaction records, inventory listings, and real‑time availability notifications, creating a single source of truth across data streams.
• Eligibility check — By querying the field, sellers can instantly verify whether a given ASIN or SKU qualifies for the Low‑Cost Store pricing model without manual cross‑referencing.
• Fee impact — Transactions marked with lowCostStore:true are processed under the program’s lower fulfillment‑fee schedule, which can affect profit calculations.
• No endpoint changes — The addition is additive; request formats, pagination tokens, and authentication mechanisms remain exactly as before.
• Backward compatibility — Existing integrations that ignore the new flag will continue to run, but they will miss the chance to apply store‑specific logic.

How the New Low‑Cost Store Field Works

1. Enrollment tagging — When a seller adds a product to the Low‑Cost Store via Seller Central, Amazon internally tags the SKU. For example, after enrolling SKU B07XYZ1234, every API response that references this SKU will contain "lowCostStore": true.
2. Finances API integration — Each financial line item linked to a Low‑Cost Store product now carries the flag. A shipment‑fee record for the same SKU will appear as , enabling accounting systems to separate reduced‑fee events from standard fees.