Overview

Amazon has rolled out three notable enhancements to the Merchant Fulfillment API v0, specifically targeting the getEligibleShippingServices operation. These changes introduce cashback visibility, adjusted cost fields, and FBM Ship+ program flags — giving Fulfilled by Merchant (FBM) sellers and their developers better tools for calculating true shipping costs and identifying program benefits at the API level.

What's New

• Cashback ItemLevelFields — The API response now includes FBM Ship+ cashback amounts directly within shipping service results, removing the need for manual tracking of rebate eligibility.
• AdjustedWithCashback Field — A new field displays carrier charges after cashback deductions, showing the effective shipping cost rather than only the base rate.
• FBM_SHIP_PLUS Benefits Flag — The Benefits field now includes an FBM_SHIP_PLUS indicator that identifies which shipping methods qualify for the program's advantages.
• Global Availability — All three enhancements apply across every marketplace and region where the Merchant Fulfillment API is available.

Cashback Visibility at the API Level

The most impactful change for cost-conscious sellers is the new cashback item-level field. Previously, FBM sellers enrolled in the Ship+ program had limited visibility into rebate amounts when programmatically evaluating shipping options. The cashback data was often siloed, requiring sellers or their software tools to separately look up whether a given shipment qualified for a rebate and how much that rebate would be. Now, this information is embedded directly in the getEligibleShippingServices response, meaning any application that queries eligible shipping methods will automatically receive cashback details alongside rate quotes. For sellers processing hundreds or thousands of orders daily, this eliminates a manual reconciliation step and enables real-time decision-making based on net shipping costs rather than gross rates.

Adjusted Cost Calculations

The new AdjustedWithCashback field complements the cashback visibility by presenting the final effective cost after deductions. This is a significant improvement for anyone building shipping cost estimation tools, order profitability dashboards, or automated carrier selection logic. Rather than fetching the base shipping rate and then separately calculating what the cost will be after rebates, developers can now pull a single field that reflects the true out-of-pocket expense. For high-volume FBM operations where margins are tight and carrier selection happens automatically, having the adjusted figure available at query time can meaningfully improve the accuracy of profitability forecasts and prevent situations where estimated shipping costs diverge from actual costs after rebates post.