MarginLock blog
Practical FBA operating guides
Searchable playbooks for fees, inventory recovery, reimbursements, compliance, and warehouse workflows that affect Amazon FBA margins.
FBA fees · 4 min read
Why your true Amazon margin moves daily — and how to watch it
Most FBA tools tell you margin monthly. MarginLock surfaces every fee and reimbursement the day Amazon books it, so you see margin shifts in time to act.
Operations · 3 min read
The weekly FBA recovery rhythm that protects margin
A simple weekly cadence keeps fee anomalies, stranded inventory, reimbursements, returns, and removals from becoming month-end surprises.
Compliance · 3 min read
Build a box compliance scorecard before Amazon charges you
Box compliance should be measured before pickup. Track weight, category mixing, dimensions, labels, and evidence at carton level.
Operations · 3 min read
Private-label and wholesale sellers need different FBA workflows
Private-label sellers optimize replenishment depth. Wholesale and arbitrage sellers optimize lot control, buy decisions, and fast recovery.
Operations · 3 min read
FNSKU-level operations beat ASIN-level guessing
Wholesale and private-label sellers need FNSKU-level control for fees, stock, prep, returns, and reimbursements. ASIN averages hide too much.
Inventory · 3 min read
IPI and aged inventory need different actions
IPI pressure and aged inventory fees often appear together, but they are solved with different SKU-level actions and review cadences.
Reimbursements · 3 min read
Returns are a reimbursement surface, not just a refund report
Returned FBA units can create leakage through missing units, wrong disposition, customer concessions, and valuation mismatch after the refund.
Warehouse · 3 min read
Multi-location stock control for FBA sellers
FBA sellers with prep centers, warehouses, and Amazon stock need one reservation model. Without it, inbound plans overpromise units.
Warehouse · 3 min read
Prep and label workflows need version control
FBA prep mistakes usually come from stale instructions. Treat prep and label rules like controlled operating procedures with owner review.
Inventory · 3 min read
Storage fee forecasting starts before inventory arrives
Monthly storage fees are predictable when teams model cube, sell-through, seasonality, and aged inventory risk before the inbound plan ships.
Operations · 3 min read
Settlement reconciliation for FBA operators
Settlement reconciliation should explain margin movement, not just balance deposits. Match orders, fees, refunds, reimbursements, and adjustments weekly.
FBA fees · 3 min read
Size-tier audits belong in your monthly FBA close
A small measurement drift can change fulfillment, storage, and placement economics. Audit size tiers monthly before fee leakage becomes normal.
Reimbursements · 3 min read
Removal orders leak reimbursements without reconciliation
Removal orders can hide lost units, damaged returns, and miscredited quantities. Reconcile every removal lifecycle before accepting the final count.
Inventory · 3 min read
Recover stranded inventory before sales are lost
Stranded inventory is usually a listing, offer, or compliance problem. A recovery queue should rank units by value, reason, and removal deadline.
FBA fees · 3 min read
Inbound placement fees should change how you build shipments
Placement fees are easiest to misunderstand at shipment creation. Model them alongside freight, receiving speed, and stockout risk before choosing an option.
FBA fees · 3 min read
Low-inventory-level fees need a days-of-supply model
The low-inventory-level fee is not just a replenishment problem. It is a SKU-level margin risk that needs daily days-of-supply tracking.
Engineering · 4 min read
Shipping SP-API: surviving Amazon's rate limits at high volume
A look at how MarginLock keeps shipment data fresh against SP-API's per-merchant rate limits, with a Postgres-backed token bucket and the trade-offs.
Reimbursements · 4 min read
Three reimbursement scenarios most FBA tools miss
Lost inventory is the obvious case. Three other scenarios — overcharged dimensions, miscounted returns, and removal miscredits — drive most missed recovery.
Compliance · 4 min read
The 50-pound box rule, and the four ways FBA teams blow it
Amazon's overweight-box penalty is one of the most expensive FBA line items. Here are four packing patterns that trigger it, and how to catch them at pack time.
Warehouse · 4 min read
How MarginLock packs your shipments without rebox loops
A walkthrough of MarginLock's bin-packing engine, why we optimize for cube fill rather than count, and how it eliminates Amazon's most common rebox triggers.