Reselling News: Whatnot Hands You the USPS Weight Adjustment Today and Poshmark Cuts Buyer Shipping to 99 Cents

Two shipping stories landed within a day of each other, and they point in opposite directions. One platform just started buying down what buyers pay. The other just stopped paying for something it used to absorb quietly on your behalf. If you sell on both, today is the day the second one starts costing you money.

Whatnot stops eating USPS weight adjustments, starting today

Beginning November 4, Whatnot no longer covers USPS weight-based carrier adjustments. When a package weighs more than what was declared on a Whatnot-generated label, USPS bills the difference, and that difference now lands on the seller. Value Added Resource reported the change, and Shopifreaks covered it as well. Whatnot describes the amount as what USPS assesses, with no Whatnot markup added on top.

The edges of the policy matter more than the headline. It applies to shipments sent on or after today, so anything already in the mail stream stays covered. Whatnot says it will keep absorbing adjustments for incorrect dimensions, for hazardous materials labeling, and for UPS shipments for the time being. It also keeps covering the label cost on up to five qualifying shipping corrections per week, as long as you update the package information before you generate the label rather than after. Sellers whose first Whatnot sale happened on or after September 5, 2026 sit outside the initial rollout and will get their own notice later.

If a charge looks wrong, you get 45 days to dispute it through the Carrier Adjustments dashboard, which shows what you declared next to what the carrier measured. USPS makes the final call, and that can take up to 90 days. Whatnot's own help page on carrier adjustments is the document to read before you file anything.

What to do: weigh the packed box, not the item. The most common source of these adjustments is a seller who weighed a sweatshirt at 14 ounces and shipped it in a poly mailer with a thank-you card at 1 pound 2 ounces. Round up when you are close to a break, because the adjustment plus the hassle costs more than the ounce you were trying to save. And fix package information before the label prints, since that is the window where Whatnot still pays.

Poshmark drops buyer shipping to 99 cents

Running the other way, Poshmark cut its standard buyer shipping charge from $6.49 to $0.99. The company's own promotion terms put the start at 12:00 a.m. PT on November 3, with no minimum purchase and the price applied automatically at checkout. A bundle from one seller counts as a single order, so the 99 cents covers the whole bundle rather than each piece. Posh LIVE show purchases are carved out, though live orders of $75 or more after discounts and before taxes ship free. Both offers are limited to US addresses, and Poshmark has not published an end date or committed to one.

The sentence sellers should read twice is Poshmark's own: the promotion does not change any seller fees or shipping charges under its policies, including overweight charges. That lands differently after the last two weeks of October, when Poshmark stopped subsidizing USPS hazmat fees and began pulling overweight label costs out of seller earnings. Buyers get a cheaper box. Sellers still own every ounce over the line.

What to do: this is a genuine tailwind on low-priced listings, where $6.49 of shipping on a $14 top was the thing killing conversion. Push your sub-$20 inventory and your bundle-friendly items while the discount runs. Then go back through anything heavy or borderline and confirm the weight on the listing is honest, because the one cost Poshmark did not take over is the one that triggers when you guess low.

Where the two meet

A 99 cent shipping promo and a weight adjustment policy look like unrelated announcements, but they resolve into the same instruction. Marketplaces are competing hard for buyers by making shipping look cheap at checkout, and they are paying for part of that by stepping back from the costs they used to quietly eat behind the scenes. The shared assumption is that the number you type into the weight field is correct.

So the cheapest upgrade available to most sellers this month is not a new platform or a new niche. It is a five dollar postal scale sitting next to the tape, used on every packed box before the label prints.

Turning small operational habits like that into margin you can actually count at the end of a month is the kind of thing members work on with me inside The Income Lab.

Hero photo of a USPS postage calculator by Atomic Taco, CC BY-SA 2.0, via Wikimedia Commons.