Amazon FBA storage fees work against sellers in two ways at once. There's the base monthly storage fee that runs every single month regardless of inventory age, and then there's the aged inventory surcharge (AIS) that stacks on top once a unit has been sitting in a fulfillment center for 181 days or longer. Many sellers focus only on one or the other. The compounding effect of both is where margins quietly disappear.
The terminology shift matters too. Amazon officially renamed the "long-term storage fee" to the "aged inventory surcharge," effective January 16, 2026. If you're still searching for the old term, you'll find it, but the current policy language uses AIS. This guide uses both terms interchangeably and explains exactly what changed in 2026.
How Amazon's base monthly storage fees work
Before getting to the surcharge, it's worth understanding the fee that runs in the background every month. Amazon's monthly inventory storage fees are calculated on your daily average volume in cubic feet, based on the size of each unit properly packaged and ready to ship per FBA requirements. The fee applies to all FBA inventory, regardless of how long it's been in the warehouse.
Monthly storage fees are charged between the 7th and 15th day of the following month. So inventory you hold in October gets billed in November.
Rates for non-dangerous goods split into two seasonal periods (source: Amazon Seller Central, Monthly inventory storage fees, G3EDYEF6KUCFQTNM):
| Size class | Off-peak: January-September | Peak: October-December |
|---|---|---|
| Standard-size | $0.78 per cubic foot | $2.40 per cubic foot |
| Oversize | $0.56 per cubic foot | $1.40 per cubic foot |
These rates apply to inventory stored for less than 22 weeks. Dangerous goods products use different rates entirely; Amazon's FBA dangerous goods page covers those specifics.
There's also a storage utilization surcharge that applies to sellers whose storage utilization ratio crosses certain thresholds. Eligibility for this surcharge requires a daily average volume of at least 25 cubic feet stored in Amazon's fulfillment network. If you're below that threshold, the utilization surcharge doesn't apply. Above it, Amazon calculates the ratio between your average inventory and average weekly units shipped, and charges additional fees if that ratio exceeds certain limits. The base monthly fee, though, applies to everyone.
Aged inventory surcharge rates (the former long-term storage fee)
The aged inventory surcharge kicks in when inventory has been in Amazon's fulfillment network for 181 days or longer (source: Amazon Seller Central, Aged inventory surcharge, GJQNPA23YWVA4SBD). It's charged in addition to the standard monthly fee, not instead of it.
Amazon calculates the surcharge two ways and applies whichever results in the higher charge: a rate based on the unit's cubic footage, or a flat per-unit minimum. For the lower aging tiers, only the cubic-foot method applies. For longer-aged inventory, the per-unit minimum kicks in as a floor.
Here are both fee schedules side by side:
Before January 16, 2026
| Days in fulfillment network | Rate |
|---|---|
| 181-210 days | $0.50 per cubic foot |
| 211-240 days | $1.00 per cubic foot |
| 241-270 days | $1.50 per cubic foot |
| 271-300 days | $5.45 per cubic foot |
| 301-330 days | $5.70 per cubic foot |
| 331-365 days | $5.90 per cubic foot |
| 366 days or more | $6.90 per cubic foot or $0.15 per unit (whichever is greater) |
From January 16, 2026 onward
| Days in fulfillment network | Rate |
|---|---|
| 181-210 days | $0.50 per cubic foot |
| 211-240 days | $1.00 per cubic foot |
| 241-270 days | $1.50 per cubic foot |
| 271-300 days | $5.45 per cubic foot |
| 301-330 days | $5.70 per cubic foot |
| 331-365 days | $5.90 per cubic foot |
| 366-455 days | $6.90 per cubic foot or $0.30 per unit (whichever is greater) |
| 456+ days | $7.90 per cubic foot or $0.35 per unit (whichever is greater) |
The 2026 update split the old "366 days or more" bucket into two tiers and raised the per-unit minimums. A unit that would have cost $0.15 at the 366-day mark now costs $0.30, and anything past 455 days costs $0.35 per unit at minimum.
Important exclusion: Clothing, shoes, bags, jewelry, and watches are excluded from the aged inventory surcharge per Amazon's policy footnote. If you sell in those categories, this surcharge doesn't apply to those ASINs.
Quick calculation example
Suppose you have a standard-size unit that measures 10 x 8 x 4 inches and has been in FBA for 280 days (271-300 day tier). Here's how to calculate the surcharge:
- Convert to cubic feet: (10 x 8 x 4) ÷ 1,728 = 320 ÷ 1,728 = 0.185 cubic feet
- Apply the cubic-foot rate: 0.185 x $5.45 = $1.01 per unit
- No per-unit minimum applies at this tier, so the charge is $1.01 per unit
If that same unit were 420 days old (366-455 day tier under 2026 rules):
- Cubic-foot calculation: 0.185 x $6.90 = $1.28 per unit
- Per-unit minimum: $0.30
- Amazon applies the greater amount: $1.28 per unit
For a small, dense unit at 420 days, the cubic-foot rate wins. For a thin, lightweight item with very low volume, the $0.30 per-unit floor might be the higher charge. Always run both calculations.
When the surcharge is assessed (and the deadline that matters)
Amazon takes an inventory snapshot on the 15th of each month. That snapshot determines which units are assessed the surcharge. The charge itself is applied to your account between the 18th and 22nd of the same month.
The deadline for avoiding the surcharge is 11:59 p.m. (PT) on the 14th. If you submit a removal or disposal order before that cutoff, those units won't appear in the 15th snapshot and won't be charged. Physical removal from the warehouse might take longer, but the fee stops at the order submission, not the physical pickup date.
Amazon also uses FIFO (first-in, first-out) logic across its entire fulfillment network. When a unit sells or gets removed, Amazon deducts that quantity from the oldest inventory first, regardless of which warehouse physically holds it. This means your inventory age isn't warehouse-specific. If you received 100 units eight months ago and sold 40 units since then, Amazon treats the remaining 60 units as the oldest 60, and they're fully subject to the surcharge.
What changed as of January 16, 2026
The 2026 update to the aged inventory surcharge introduced three meaningful changes:
- The single "366+ days" tier was split into two tiers: 366-455 days and 456+ days
- The per-unit minimum for the 366+ tier increased from $0.15 to $0.30
- A new top tier was created at 456+ days with a $0.35 per-unit minimum and $7.90 per cubic foot rate
If you were tracking AIS costs under the old schedule and haven't updated your cost models, your projections for older inventory are likely understated.
Last updated: September 2026. Amazon can and does revise fee schedules; verify current rates against the Aged inventory surcharge page (help ID: GJQNPA23YWVA4SBD) and Monthly inventory storage fees page (help ID: G3EDYEF6KUCFQTNM) before making financial decisions.
How to estimate your surcharge using Seller Central tools
Finding at-risk inventory before the snapshot
In Seller Central, go to Inventory > FBA Inventory (also called Manage Inventory Health). You can filter by "Time in fulfillment center" to identify units already past 181 days, and the tool will also show items approaching that threshold. Amazon displays a "within 60 days" projection, which gives you a forward-looking view of what's about to age into surcharge territory.
Auditing charges already assessed
The Aged Inventory Surcharge report (accessible under Reports > Fulfillment in Seller Central) gives you itemized details of recent surcharge charges. The key columns and how they connect:
| Column | What it means |
|---|---|
| Snapshot date | The 15th-of-month date when the inventory count was taken |
| Charged quantity | Number of units charged in that tier |
| Per-unit volume | The cubic-foot volume Amazon used for that ASIN |
| Surcharge age tier | Which aging bucket (e.g., 271-300 days) was applied |
| Charged amount | The total charge for that line item |
Amazon's formula: amount-charged = rate-surcharge x qty-charged, where rate-surcharge = per-unit-volume x surcharge rate (or the per-unit minimum if it's higher).
Practical workflow
- Export the AIS report for the last 60-90 days
- For each ASIN, recalculate the expected charge using the greater-of rule (cubic-foot rate vs. per-unit minimum)
- Compare your calculation to the charged amount column; flag discrepancies
- Cross-reference with FBA Inventory to see which of those ASINs are still in the network
- Make a removal or markdown decision before the next 14th cutoff
Calculation checklist before committing numbers:
- Confirm the correct size tier (standard vs. oversize)
- Use the packaged dimensions, not bare product dimensions, for cubic-foot conversion
- Divide L x W x H (in inches) by 1,728 to get cubic feet
- Check whether the per-unit minimum applies at that aging tier
- Run both methods and take the higher result
Sellers who use automated repricing tools like Informed Repricer are already tracking sell-through velocity, which directly affects how quickly inventory ages. Faster Buy Box wins mean faster turnover, and faster turnover is the most efficient way to prevent inventory from crossing the 181-day threshold in the first place.
Options for avoiding or reducing the surcharge
Amazon offers three primary paths when you identify at-risk inventory:
Sell through via Amazon Outlet. Amazon Outlet accepts overstocked or aged inventory at a minimum 20% discount off the original price. If the product has margin to absorb that discount and genuine demand exists, this is the cleanest outcome. You recover revenue rather than paying removal fees.
Submit a removal or disposal order. Go to Inventory > Manage FBA Inventory, select the affected ASINs, and create a removal order before 11:59 p.m. PT on the 14th. Disposal is cheaper than removal if the product has no resale value; removal makes sense if you can liquidate it elsewhere or reroute it.
Set automated removals. Seller Central lets you configure automatic removal triggers based on inventory age thresholds. This is a useful guardrail if you're managing a large catalog and can't consistently do manual reviews.
Decision framework
The right choice depends on three variables: margin remaining, expected sell-through velocity, and how many more 15th-of-month snapshots the inventory will likely survive.
If projected velocity is strong enough to sell through before the next snapshot, mark it down aggressively and leave it. If velocity is weak and margin is thin, removal stops the bleeding. If you have consistent overstocking patterns across multiple ASINs, automated removals prevent the problem from recurring without requiring monthly manual intervention.
The "advanced prevention" mindset means reviewing your FBA Inventory Health report around the 13th-14th of every month, specifically filtering for units approaching 181 days or already in a surcharge tier. A 30-minute monthly review on that cadence prevents multi-month compounding charges on the same units.
Common mistakes sellers make with aged inventory surcharges
"I'll submit a removal after the 15th and avoid the charge." The snapshot is taken on the 15th. Submitting a removal after that date prevents charges in the following month's snapshot but does nothing for the current month's charge. The deadline is 11:59 p.m. PT on the 14th, not the 15th.
"I'll just check the age of inventory in the warehouse closest to me." Age is calculated at the network level, not the warehouse level. Amazon uses FIFO logic across all fulfillment centers simultaneously. A unit sold from a Phoenix warehouse reduces the age counter for your oldest inventory globally, regardless of where those oldest units are physically sitting.
"My clothing ASINs will get hit too." Clothing, shoes, bags, jewelry, and watches are excluded from the aged inventory surcharge per Amazon's policy. If you're in those categories, verify your ASIN classification, but you shouldn't be seeing AIS charges on those items.
"I'm only paying the per-cubic-foot rate." For inventory past 365 days (under the 2026 schedule, past 366 days), there's a per-unit minimum. If the cubic-foot calculation produces a number lower than the per-unit minimum, Amazon charges the minimum. Small, lightweight items are especially susceptible to having the per-unit minimum override the volume-based rate.
If you notice charges that seem miscalculated, particularly related to cubic-foot measurements, check whether Amazon has your product dimensions on file correctly. Incorrect dimensions in Amazon's system can lead to overstated volume-based charges; the Seller Central help documentation references a remeasurement process for disputing recorded dimensions.
What to do this month
The immediate action list is short:
- Open FBA Inventory / Manage Inventory Health and filter for units already past 181 days and units within 60 days of that threshold
- Pull the Aged Inventory Surcharge report for the last two billing cycles and confirm you understand what you were charged and why
- For any at-risk ASINs, run the greater-of calculation (cubic-foot vs. per-unit minimum) to project what the next snapshot will cost
- Submit removal or disposal orders for any units where the math doesn't favor holding by 11:59 p.m. PT on the 14th
The aged inventory surcharge doesn't replace the base monthly storage fee. Both run simultaneously on the same units. Holding slow inventory past 181 days means paying both layers every month the unit stays there, with rates that escalate steeply as the unit ages past 270, 365, and now 455 days. The cost of inaction compounds faster than most sellers expect.