The hard part of a marketplace is not the catalogue or the cart. It is the money. Splitting at the source through the payment provider, a payout cycle with a written rule, and refund handling designed from the start are what separate a healthy operation from an endless reconciliation spreadsheet.
Building the storefront is known work. What sinks projects is the first Monday of the following month, when thirty sellers want to know why the amount that landed in their account does not match what they calculated.
Split at the source, not in your own account
The first serious mistake is collecting everything into a single platform account and paying sellers later by transfer. It looks simple and creates two real problems.
The first is fiscal. The entire amount now flows through as platform revenue, which changes your tax position completely. The second is operational: any refund becomes a manual attempt to claw back money that has already left.
The correct answer is a split performed by the provider itself, whether Stripe Connect, Adyen for Platforms or a local equivalent. Each seller has a connected account, the charge is divided at the moment it is created, and the platform receives only its commission. Refunds reverse proportionally with nobody intervening.
The payout cycle needs a name and a rule
Write it into the contract and into the code, using the same words in both:
- When funds become available. On payment confirmation? On confirmed delivery? Seven days later, to cover the dispute window?
- Who absorbs the processing fee. The seller, the platform, or split between them?
- What happens to shipping. Does it count towards commission? Usually it does not, and usually nobody agrees this in advance.
- Refunds after payout. Deducted from the next cycle? And if there is no next cycle?
Every marketplace that descended into reconciliation chaos left at least one of those open.
Every movement is an immutable entry
Do not keep the seller’s balance in a field you update. Keep entries: sale, commission, fee, refund, manual adjustment, payout. The balance is their sum, never a number somebody wrote over the top.
It feels like excessive rigour until the first dispute. With entries, you open the statement and show line by line how the figure was reached. With a balance field, you have the system’s word against the seller’s spreadsheet, and the spreadsheet tends to win that argument.
It is the same reason accounting has used double entry for six hundred years. It is not bureaucracy. It is the only way to audit.
The mistakes that only surface in production
Stock shared between sellers
Two sellers list the same product with one unit each. The buyer puts both in one cart and one of them is out of stock. There is a single order and a single payment, and the split has to be partially undone. Decide in advance: reserve at cart, partial cancellation, or block that combination.
Sellers without an approved account
Opening an account with the payment provider takes hours to days and can be rejected. If a seller can publish before approval, you will sell a product with nowhere to send the money. Block publishing until the account is active.
Cancellation midway
An order with three sellers and one cancels. Shipping recalculated, commission recalculated, partial refund. If that is not modelled from the beginning it becomes a manual adjustment, and manual adjustments in a money flow are where an operational slip turns into a loss.
The seller dashboard is not an accessory
It decides whether support handles three tickets a month or thirty a day.
The minimum it has to show: orders with current status, a statement with every entry, the date of the next payout, the reason for any deduction, and the full history of previous payouts with receipts.
A seller who can answer “why did I receive this amount” on their own does not open a ticket. Across hundreds of sellers, that is the difference between needing one support person and needing five.
Start small on purpose
A marketplace with ten hand-picked sellers, onboarded manually by the team, teaches you more in two months than six months of planning. The payout rules come out right because they were corrected by real complaints rather than by meeting-room hypotheticals.
Need this solved at your company?
A twenty minute call is usually enough to tell whether it makes sense, and you talk straight to the engineer who builds it.