How the aged inventory surcharge works
Amazon charges an extra monthly fee on FBA inventory that has been in a fulfillment center too long. It is charged on top of normal monthly storage, not instead of it, and it escalates sharply the longer stock sits.
Two things matter here. First, the surcharge now starts at 181 days, not 271 — Amazon lowered the trigger, and it catches sellers who still plan around the old threshold. Second, the jump between 241–270 days and 271–300 days is brutal: $1.50 to $5.45 per cubic foot, a 3.6× increase for thirty days. That cliff lands for most sellers right as peak storage rates begin — see how the two charges stack in Q4. That cliff, not the 365-day rate, is where most avoidable surcharge cost is incurred. The $0.15 per-unit floor on the 365+ band means small items are charged at least that much per unit even when their cubic footage implies less.
A worked example
500 units of a standard-size product measuring 8 × 5 × 2 inches — 0.046 cubic feet per unit, or 23.15 cubic feet in total — that have passed the 365-day mark:
Over $2,100 a year to store 500 units that are not selling. In most cases the correct decision is not to optimise this number but to remove the stock — weigh the surcharge against what removal or disposal costs before you decide.
What to do about aged stock
- Act before day 241, not after. The surcharge is entirely predictable — you know the day each unit arrived. Clearing stock before it crosses into the 271-day band avoids the 3.6× step up, and a discount at month eight is almost always cheaper than a surcharge at month ten.
- Compare the surcharge against a removal. Removal or disposal costs a fixed fee per unit. If the annual surcharge exceeds that, removal wins, even before you count the capital tied up.
- Discount deep enough to actually clear it. A 10% discount that moves nothing costs more than a 40% discount that empties the shelf, because the surcharge keeps compounding monthly.
- Run ads at a loss if the maths works. Selling below cost can beat paying $6.90 per cubic foot every month. Use the ACoS calculator to size the loss you can accept.
- Fix the cause, not the symptom. Aged inventory is nearly always an ordering problem. The restock calculator sizes orders against real velocity instead of optimism.
Why FIFO matters here
The surcharge is assessed on the age of specific units, so which units you consider "sold" is not an accounting abstraction. If you track cost on a blended average, your books will not tell you that a particular batch has been sitting for eleven months and is about to attract a surcharge. Lot-level FIFO costing ties each unit to the purchase it came from — so aged stock shows up as an ageing lot before it shows up as a fee.
This calculator estimates exposure for one product. To see age bands across your whole catalogue, with alerts before units cross each surcharge band, SellerGuards inventory intelligence tracks it from your real SP-API data.