Which of your FBA units will get an aged inventory surcharge? Read the age columns before the next charge

The monthly storage fee applies to everything in the warehouse. The aged inventory surcharge applies only to units that have been there too long, and it comes on top of the storage fee. In Amazon's own report the charged age bands start at 181 days.

Stock that arrived at the beginning of April turns 181 days old at the end of September. If you sent in extra units in spring for the summer, some of them are crossing that line now, just as the higher Q4 storage rate starts.

Which units, in which band, and what it is expected to cost: all of it is in one report, and every claim below points at a column in it.

Where the report is

In Seller Central it sits in the Inventory menu, under Inventory Planning, where the FBA inventory view can be downloaded. Through the API it is the FBA Inventory Planning report (GET_FBA_INVENTORY_PLANNING_DATA). The column names below are from the downloaded file.

These columns matter:

• sku, asin, product-name. Which product.
• available. Units you can sell today.
• inv-age-0-to-90-days, inv-age-91-to-180-days, inv-age-181-to-270-days, inv-age-271-to-365-days, inv-age-366-to-455-days, inv-age-456-plus-days. How many units are in each age band.
• quantity-to-be-charged-ais-181-210-days and the matching columns up to 456-plus-days. How many units the surcharge is expected to hit, band by band.
• estimated-ais-181-210-days and the matching columns. What that is expected to cost, band by band.
• units-shipped-t30, units-shipped-t90. How many units you sold in the last 30 and 90 days.
• recommended-action, recommended-removal-quantity. What Amazon suggests you do.
• Inventory age snapshot date. The day the age figures are from.

The age columns overlap

The report does not give you one set of age bands, it gives you several. Next to the six main bands you will find inv-age-0-to-30-days, inv-age-31-to-60-days and inv-age-61-to-90-days, which split the first band, and inv-age-181-to-330-days and inv-age-331-to-365-days, which cut the middle of the year differently.

If you add up every column that starts with inv-age, you count the same units twice. Use the six main bands. In a real report we checked, they added up to the available figure on every row, give or take one unit.

Two dates in one file

The report has a snapshot-date, and it has an Inventory age snapshot date. They are not the same. In the report we checked, the age figures were three days older than the rest of the file.

That is where the one-unit gaps come from: a unit sold or received in those three days is in available, but not yet in the age bands. It does not matter for a decision. It does matter if you try to reconcile the numbers to the unit and wonder why they never match.

The charge columns are not the age columns

It is tempting to read the 181-to-270 band and assume that is what will be charged. The report has separate columns for that, and they do not always agree. We saw rows where the quantity to be charged was higher than the count in the matching age band.

Use the age bands to decide what to do with a product. Use the quantity-to-be-charged-ais and estimated-ais columns when you want to know the money.

The number that tells you something

Old stock on its own is not a problem if it is about to sell. Compare two columns for each product: the units in the bands from 181 days up, and units-shipped-t90.

If the product sold more in the last 90 days than it has in the old bands, those units will most likely leave before they cost much. If it sold a handful and has hundreds of old units, the surcharge will keep coming every month until you act. That is the product to decide about now: a promotion to move it, a removal order, or a disposal if the product will not sell at all.

Look at the 91-to-180 band as well. Those units are not charged yet, but they are the ones that cross 181 days during Q4.

Two traps

Don't take recommended-action at face value. Amazon fills it in for every product. In the report we checked it said "Advertise listing" on most rows, including the ones the same report flagged as low traffic. Advertising a product that does not convert adds ad spend to the storage cost. Check the sales first.

Don't overcorrect. The same report has columns for the low-inventory-level fee (fba-minimum-inventory-level, and whether the fee was applied this week). Amazon charges that one when you hold too little stock of a product that sells. Removing old units is right for slow products. Doing it across the board can move a good product into the other fee.

Ten minutes a month

Download the FBA Inventory Planning report. Keep the six main age bands and units-shipped-t90. For each product, add up the units from 181 days up and put the 90-day sales next to it. Sort by the old units.

The top of that list, where sales are low, is where the surcharge comes from. Decide about those before the next charge, and check the 91-to-180 band for the ones that come after them.