Short answer, checked 2026-08-31: Amazon now lets FBA sellers pay to push additional products into the Sub Same Day (SSD) network by setting a per-unit reservation fee, and that fee is charged only on units that actually ship through SSD. Amazon’s own help page never calls it a bid, but it works like a capped one: in Amazon’s words, “you’re never charged more than the reservation fee you set,” and the number you set is one of the inputs Amazon uses to rank competing requests. Nothing is due up front, and if no units ship through SSD during your placement period, nothing is charged.
The wording matters because two different things are now both called “Sub Same Day,” and only one costs money. This guide separates them and labels everything second-hand as second-hand.
Two Sub Same Day programs, only one of which you pay for
Amazon runs a free, algorithmic SSD placement program and has now added a paid request layer on top of it. They live on separate help pages.
| Free SSD placement | SSD Placement Reservation | |
|---|---|---|
| Who picks the ASINs | Amazon, from demand signals | You, from Amazon’s list |
| Cost | None | Per-unit reservation fee you set |
| When you pay | Never | On units shipped via SSD |
| Where you act | Nowhere | Sub Same Day tab, Capacity Manager |
| Amazon help page | FBA Sub Same-Day Delivery | FBA Sub-Same Day Placement Reservation program |
On the free program, Amazon’s page is unambiguous (checked 2026-08-31): “All sellers are eligible for the program, and there is currently no additional fee for the service.” When an ASIN is selected, “Amazon will automatically move inventory into dedicated fulfillment centers and apply the fastest delivery option to the most competitive offers on Amazon.”
The paid layer exists because that automatic selection is capacity-bound. Amazon says it already makes over 100,000 FBA products eligible for SSD delivery, across a network it describes as serving 2,300+ metro areas with delivery in two to five hours. The reservation program is how you nominate something Amazon’s model did not pick. Products Amazon already placed for free are unaffected: “Products we’ve already placed in SSD on your behalf stay there at no cost.”
What the reservation fee is, and why it is a ceiling
You submit a request against a single ASIN with three inputs: a placement period, your projected total FBA units per month in that period, and the reservation fee in dollars per unit. Amazon then shows a system-calculated “Estimated Sub Same Day Units” figure derived from your projection and historical patterns.
Amazon defines the fee as “the per-unit amount you will pay if reservation is granted and when a unit ships through SSD.” Three consequences follow, all stated on the page:
- It is a ceiling, not a rate you are quoted. “You pay only when a unit ships from the SSD network, and you’re never charged more than the reservation fee you set.”
- Billing is retrospective. “Reservation fees are charged at the end of each placement period based on the number of units that shipped through SSD.”
- There is no floor. “The reservation fee applies only to units that ship through SSD during your placement period. If no units ship, you will not be charged the reservation fee. There is no minimum usage requirement.”
Amazon also states plainly: “Participation is optional, with no upfront cost.”
The word bid comes from elsewhere: EcommerceBytes, reporting on 29 August 2026, quoted Amazon’s seller invitation as saying “You pay only for units that actually ship through Sub Same Day, at the per-unit price you bid.” That is invitation copy relayed by a trade publication, not help-page language. “Reservation fee” is the term you will see in Capacity Manager.
Which of your ASINs can even be entered
You do not pick from your whole catalogue. Amazon publishes a downloadable list of eligible ASINs in the Sub Same Day tab, gated on seven conditions.
| Requirement | Note |
|---|---|
| FBA-fulfilled | FBM and SFP are out |
| New condition | Used and refurbished are out |
| Standard-size | Oversize tiers are out |
| Not large, heavy, or expensive | Thresholds unpublished |
| Not a dangerous good | Hazmat blocks entry |
| Healthy inventory levels | Judged in FBA Manage Amazon Inventory |
| Not already in SSD | You cannot pay for what is already free |
Two notes from Amazon’s FAQ. The list is not static — “The eligible list refreshes weekly,” so an ASIN you fix this week can appear in a later download. And a missing ASIN is, per Amazon, either already in SSD or failing one of the criteria above; converting to FBA, improving inventory levels, and resolving a hazmat classification are the named remedies.
To see what is already in the network for free, filter FBA Manage Amazon Inventory to “Sub Same Day delivery” under Services, or read the “Fulfillment Service and Programs” column of the FBA Inventory Report.
How requests are granted, and what your number is competing against
This is what makes it an auction in behaviour if not in name. Amazon allocates SSD capacity monthly: at the beginning of each month, all requests for the next immediate placement period are evaluated together.
The ranking inputs are published. Amazon states: “Our process prioritizes requests based on a combination of customer value, reservation fee, Amazon unit economics and inventory health until available capacity is fully allocated.” Your fee is therefore one of four factors, not the whole contest — a high fee on a product with weak demand signals or thin stock is not a purchase, it is an entry.
Amazon also caps expectations on the grant itself: “A granted request does not guarantee a specific sales volume, as actual SSD units depend on customer demand.” Granted status shows in Your SSD Placement Requests and is confirmed by email.
The free-placement page names the same preferences from the other direction — customer value, price competitiveness, inventory health — and warns that “Fluctuations between healthy and low stock reduce your chances of placement.” If your ASIN is losing the Featured Offer or bouncing in and out of stock, fix that before setting a fee.
The inventory conditions are the real commitment
The fee is the visible cost. The obligation is inventory, and Amazon builds three checkpoints into the timeline.
- T-30 days. Amazon reviews whether your inventory levels are healthy and emails restock steps if action is required.
- T-14 days. A second review, with a final notification if you are still short.
- During placement. Falling below healthy levels means your products “may be available in fewer SSD locations,” reducing coverage and demand lift. Amazon adds that unhealthy inventory levels “may affect your future ability to participate in this program.”
The structural reason is capacity: Amazon states that “SSD fulfillment centers are smaller, so they hold less inventory per product than a standard fulfillment center.” Winning placement means committing to replenish into a network that holds less per SKU than you are used to — which pushes the work back onto your reorder points and safety stock, not onto the bid. Our inventory tracking guide covers the arithmetic.
One relief worth knowing: there is no penalty fee for running thin. Amazon states “there are no additional SSD-related fees if you do not maintain healthy inventory levels” — the cost of running out is lost sales and a weaker position next cycle, not a charge.
The cancellation window, in one line
Free before granting, locked after. Amazon: “You can cancel a submitted request at no cost at any time before it is granted.” And then: “Granted requests cannot be canceled within 30 days of the placement period, or during the placement period.” Your request expiration date must also fall within 28 days of your placement period start.
So the decision is reversible right up to the grant email, and effectively irreversible for roughly the last month before placement plus the placement itself.
About that 12% figure
Both Amazon pages carry a sales-lift number, and both attribute it to Amazon. On the reservation page: “Products placed in this network have experienced 12% higher sales on average compared to core Fulfillment by Amazon (FBA) delivery.” On the free-placement page the phrasing is softer — products “can see up to 12% higher sales.”
Two things to hold onto. It is Amazon’s own figure, not an independent measurement, and Amazon publishes no methodology, sample, category breakdown, or period alongside it. And Amazon itself hedges it in a note directly under the claim: “This is a network-wide average. Your results may vary based on your product category, pricing, and local demand.”
There is also a selection problem the caveat does not name. Products currently in SSD are there because Amazon’s model expected them to sell fast, so part of any observed lift is the selection, not the speed. An average measured on Amazon’s picks is weak evidence for a product Amazon’s model passed over — which is, by definition, every product you would pay to enter.
Working out what to set
Amazon’s FAQ suggests using Profit Analytics to review your per-unit margins, then considering what a sales increase would mean at those margins relative to the fee. That is the right shape. Filled in — illustrative numbers, not Amazon data:
Suppose a SKU nets $6.00 per unit after referral and fulfilment fees, and you sell 1,000 units a month. A 12% lift is 120 extra units, worth $720 in margin. But the fee is charged on every unit that ships through SSD, not only the incremental ones. If SSD ends up handling 400 units at a $0.50 reservation fee, that is $200 charged against $720 of upside — workable. At $2.00 per unit it is $800 against $720, and the placement loses money even though the lift was real.
The break-even test is therefore (expected incremental units x unit margin) ÷ (expected total SSD units), and that quotient is the highest fee worth setting. Two inputs decide it, neither of them your fee: how much of your volume routes through SSD, and how big the lift is for your category. Amazon estimates the first for you in the submission form. Nobody can hand you the second.
So treat the first period as a measurement, not a bet. Amazon provides a performance summary and fee charge report in the Sub Same Day tab at the end of each placement period; read against a clean pre-period baseline, that is the only category-specific lift number you will ever have. If you do not already track unit-level contribution reliably, fix that first — our guides to FBA unit economics and profit analytics tools cover what most sellers miss before adding another per-unit charge to the fee stack.
Common mistakes
- Reading the fee as a subscription. It is per unit shipped, charged in arrears, with no minimum. A granted request that ships nothing costs nothing.
- Bidding on the wrong SKU. The four ranking inputs include Amazon unit economics and customer value. A slow SKU with a big fee attached still loses to a fast SKU with a small one.
- Ignoring the lock window. Cancellation is free until grant, then closed for the 30 days before placement and throughout it.
- Paying for what you already have free. ASINs Amazon already placed are excluded from the eligible list precisely because they cost nothing. Check the inventory filter before you go looking for them.
- Treating 12% as a forecast. It is Amazon’s network-wide average over products Amazon selected, hedged by Amazon, with no published methodology.
Frequently Asked Questions
Is the Amazon Sub Same-Day seller bid the same as a reservation fee?
They are the same number. Amazon’s help page says “reservation fee” throughout; “bid” comes from the seller invitation EcommerceBytes quoted on 29 August 2026. Functionally it is a capped bid — Amazon ranks requests partly on it and never charges above it.
What does Sub Same Day cost an FBA seller?
Nothing for the free program, which Amazon states carries “no additional fee for the service.” For the reservation program the cost is whatever per-unit fee you set, charged at the end of the placement period on units that actually shipped through SSD. There is no upfront cost and no minimum.
Who gets invited to the SSD Placement Reservation program?
Amazon’s help page does not describe an account-level invitation gate; it describes an ASIN-level one, with your eligible products downloadable from the Sub Same Day tab in Capacity Manager. EcommerceBytes reported that Amazon invited FBA sellers to participate. If the Sub Same Day tab is not showing for your account, that is the sharpest signal available.
Can I cancel after Amazon grants my request?
Not close to the placement. Cancellation is free at any time before grant, but Amazon states that granted requests “cannot be canceled within 30 days of the placement period, or during the placement period.”
What happens if I run out of stock mid-placement?
Your products may reach fewer SSD locations, reducing the coverage and demand lift you were paying for. Amazon says it keeps fulfilling orders from whatever SSD inventory remains and that no extra SSD fees apply — but unhealthy levels may affect your ability to participate in future periods.
Conclusion
SSD Placement Reservation is the first time Amazon has let FBA sellers buy into a delivery-speed tier the algorithm otherwise assigns for free, and Amazon has been unusually clear about the mechanics: capped per-unit fee, charged in arrears, no minimum, cancellable until granted. The unclear part is the part that decides whether it pays — how much lift a product Amazon’s model declined to place will actually get, on which a 12% network average is the weakest kind of evidence.
So make the first move a small, measurable one: one ASIN with reliable stock and known unit margin, a fee below the break-even quotient, and the end-of-period report read against a clean baseline. The program’s design supports that — nothing is owed until units ship.
Sources checked 2026-08-31: Amazon Seller Central, FBA Sub-Same Day Placement Reservation program and FBA Sub Same-Day Delivery; EcommerceBytes, 29 August 2026.