Amazon Hikes, TikTok Shop Cuts: The May Fee Divergence

For the first time in recent memory, the two marketplaces most cross-border sellers care about moved their fulfillment economics in opposite directions in the same month. That isn't a coincidence of release calendars. It's a strategic divergence with consequences for inventory placement, pricing, and what platform you optimize next quarter.

If you ship anything over 16 pounds — supplements at scale, small appliances, fitness equipment, pet products, anything bundled into a heavier kit — your unit economics on TikTok Shop just got better and your unit economics on Amazon just got worse. The gap isn't large enough to move a brand overnight. It is large enough to change which SKUs you push, which platform you list new heavy variants on, and how you model H2.

This isn't last month's "Amazon DD7 cash squeeze" story — that one was about working capital. This one is about per-unit margin, and it's happening at a platform-vs-platform level rather than inside Amazon's own stack.

Amazon's surcharge is no longer just an FBA problem

On April 3, Amazon announced via Seller Central that it would apply a 3.5% "fuel and logistics-related surcharge" to fulfillment fees. The first wave hit Fulfillment by Amazon (FBA) in the US and Canada, plus Remote Fulfillment with FBA into Canada, Mexico, and Brazil, on April 17, 2026. The second wave — the one that closed in this month — hit Buy with Prime in the US and Multi-Channel Fulfillment (MCF) in the US and Canada on May 2, 2026.

The May 2 expansion matters more than it reads. MCF is how a lot of mid-sized cross-border sellers use Amazon's fulfillment network to ship orders that originated on Shopify, TikTok Shop, Walmart, or their own DTC site. Buy with Prime is Amazon's wedge into non-Amazon storefronts. Until May 2, both were the way sellers used Amazon's logistics without paying Amazon a marketplace cut. After May 2, both carry the same surcharge as native FBA orders.

Amazon's own arithmetic: the surcharge averages $0.17 per unit on a standard-size US FBA item, calculated against the fulfillment fee, not the sale price. Heavier and oversize items absorb more. Per Digital Commerce 360, the trigger was a Q1 oil price shock — a barrel of crude jumped from roughly $60 on February 3 to $112 on April 3, attributed to disruption in the Strait of Hormuz tied to the US–Iran conflict.

Amazon is not the only carrier passing the cost through. USPS layered its own temporary 8% package surcharge on Priority Mail Express, Priority Mail, Ground Advantage, and Parcel Select, effective April 26, 2026 through January 17, 2027 pending regulatory approval. That closes a popular workaround: switching from FBA to direct USPS Ground Advantage no longer escapes the surcharge regime — it trades 3.5% for 8% on the segment going via USPS.

TikTok Shop cut FBT fees the same month — and in the weight bands that hurt most on Amazon

On May 20, TikTok Shop updated its Fulfilled by TikTok (FBT) rate card with reductions specifically targeting the heavier end of the catalog. Per the official Seller University rate card, single-unit fulfillment fees on 16lb to 50lb weight tiers dropped by $0.10 to $5.00. Multi-unit fees on 20lb-plus tiers dropped by $3.50 to $5.00. Sellers enrolled in Ships in Own Container (SIOC) can earn an additional discount of up to $0.80 per single-unit item.

There is no surcharge offsetting the cut. The headline number is the net.

The targeting is deliberate. Heavy SKUs are the worst economics on FBA — Amazon's standard-fee table escalates aggressively above 16 pounds, and the May 2 surcharge is calculated as a percentage of the fulfillment fee, so it bites hardest exactly where the base fee is highest. TikTok Shop is buying volume in the categories where Amazon's pricing pain is most acute right now: supplements (jars and powders), pet food, small appliances, fitness, home goods. Several of these categories are also where TTS is currently chasing Amazon for share — the Q1 2026 TikTok Shop US top-10 was led by Toplux Magnesium Complex at $9.5M Q1 revenue across 414,503 orders, with one month topping 1 million units. That is exactly the kind of heavy, repeat-purchase, mid-weight SKU profile the new FBT rate card subsidizes.

For a 20lb SKU currently fulfilled by FBA at, say, an $11 fulfillment fee, the May 2 Amazon surcharge adds roughly $0.39 per unit. For the same SKU moved to FBT in the new rate card, the per-unit fulfillment fee falls by $3.50 to $5.00. The combined swing is in the low-single-digit dollars per unit. On a product with a 25% gross margin and a $30 ASP, that's a multi-point margin difference per unit — not a "round to zero" event.

Why the divergence is structural, not noise

Both moves are downstream of the same macro shock. Amazon is reacting to fuel costs that hit its own line-haul and last-mile network. TikTok Shop is reacting to a competitive opportunity — Amazon visibly raising fees in the weight bands where TTS has been trying to build a fulfillment moat.

TikTok Shop's FBT network is younger, smaller, and less utilized than FBA. The 16–50lb weight tier was an under-served corner of its rate card; subsidizing it now is cheap on a per-warehouse basis and aggressive on a competitive basis. The rate card change has no expiration date listed, but FBT fee tables historically move every 6–12 months. Treat the May 20 rate as a planning baseline through year-end and an unknown beyond.

What this means for sellers this week

1. Reweight your fulfillment by SKU weight class, not by platform. Anything 16lb and up where you control both an Amazon and a TikTok Shop SKU should be repriced and reforecast against the new FBT rate card. Sellers who are FBA-only on heavy items should at minimum pull the comparable FBT quote before the next reorder. The Amazon Revenue Calculator and Profit Analytics tools were updated for the surcharge; the TikTok Shop FBT rate card is the comparable input on the other side.

2. Multi-Channel Fulfillment is no longer a clean side-door. If you've been using MCF to fulfill Shopify or TikTok Shop orders to keep one inventory pool, the May 2 surcharge adds 3.5% per order on top of an already higher per-unit MCF fee than native FBA. The math on consolidating inventory at FBA-MCF vs. splitting into FBT or 3PL fulfillment just shifted. Run the comparison.

3. SIOC is now worth the packaging work. For TTS sellers in heavy categories, the $0.80 per-unit incremental SIOC discount stacks on top of the May 20 fee cut. SIOC requires shipping in original packaging without overbox — operationally annoying, financially material on volume. If you've punted on SIOC because the savings didn't justify the SKU re-packaging work, the new combined number probably does.

4. Don't model the surcharge as temporary. Amazon's language is "temporary" — historical pattern says otherwise. Build H2 cost models with the 3.5% as a permanent line item; if Amazon ever rolls it back, you'll be early to the margin upside.

5. USPS-as-escape-hatch is closed. The 8% USPS package surcharge on Ground Advantage and Priority closes the most popular "go direct to USPS" workaround. The net: there is no cheap way out of the 2026 US fulfillment cost cycle, only better and worse choices.

The long view

The May divergence isn't just an opportunistic price move by TikTok Shop. It is the first time in this cycle that a major US marketplace has used fulfillment pricing — not commission, not ad fees, not GMV bonuses — as the lever to recruit Amazon sellers in specific weight classes. That is a more durable wedge than any of the prior TTS plays, because it changes the cost-of-goods math at the unit level rather than the campaign level.

Over the next 6–12 months, expect three things. First, more cross-border sellers will multi-home with SKU placement sorted by weight class — heavier SKUs at FBT, lighter and faster-velocity SKUs at FBA where Prime conversion still pays for itself. Second, Amazon will likely respond to FBT competition in heavy bands either with its own selective fee cuts or with non-price incentives (better placement, additional Brand Registry features). Third, the "temporary" surcharge will not be temporary. Crude back at $60 will not produce a corresponding fee rollback; the line item will become a permanent feature of the FBA cost table by Q4.

The cleanest read of this month: Amazon is letting heavy SKUs subsidize Prime delivery economics, and TikTok Shop just made it cheaper to walk those SKUs across the street. Sellers who treat the May 2 and May 20 dates as a single repricing event — rather than two separate platform announcements — will end Q3 with materially better margin than sellers who absorb each surcharge in isolation.