E-commerce finance: contribution margin

What good finance answers

An e-commerce finance review should connect the order to the cash and margin it produced:

• What is the contribution margin by product, order, campaign, marketplace, and channel?
• Does landed cost include supplier price, freight, duties, packaging, and other required costs consistently?
• Which marketplace, payment, fulfillment, and software fees changed from the previous period?
• What do returns and refunds cost after reverse logistics, damaged stock, and lost acquisition spend?
• Can available cash support purchase orders and inventory lead time before the related payout arrives?

Use the product and channel contribution-margin workflow to move beyond blended gross margin.

Pressure points

Data is split across orders, payouts, and books

Store revenue, marketplace settlements, processor fees, advertising, fulfillment invoices, and accounting entries may use different dates and identifiers. Reconcile the population before comparing product or channel profit.

Landed cost changes between purchase cycles

Supplier price, currency, freight, duty, packaging, and receiving cost can change while the storefront price stays fixed. Track cost by purchase batch or approved costing method so current margin does not rely on an outdated standard.

Fees are deducted before cash arrives

Marketplace and processor payouts often combine sales, fees, refunds, reserves, and adjustments. Review marketplace and payment fees against settlement detail instead of posting the net deposit as revenue.

Returns create delayed margin loss

The original sale and later refund may land in different periods. Connect return reason, product condition, refund, restocking, reverse shipping, and recoverable inventory to see the full effect.

Operating rhythm

Cadence	Review	Decision output
Weekly	Payout exceptions, stock risk, returns, ad spend, expected supplier payments	Pricing, promotion, reorder, and cash actions
Monthly	Product and channel margin, landed cost, fee changes, inventory reconciliation	Assortment, channel, vendor, and cost corrections
Quarterly	Inventory method, supplier terms, return patterns, channel mix	Purchasing plan, policy review, and capital allocation

When purchasing decisions create a timing problem, use the cash timing and liquidity workflow with expected payouts and supplier commitments.

AI with controls

AI can match settlement lines, classify fees, calculate contribution margin, and locate unusual product or channel movements. It cannot repair missing order identifiers, inventory counts, or an undefined costing policy.

A controlled e-commerce workflow should:

1. State the order, payout, return, and accounting periods included in the review.
2. Reconcile gross sales to discounts, refunds, fees, reserves, and cash received.
3. Link margin findings to SKU, order, channel, settlement, vendor, and cost records.
4. Flag missing landed-cost components, negative inventory, duplicate fees, and timing differences.
5. Keep inventory policy, tax treatment, pricing, purchasing, and write-off decisions with qualified people.

MosoFin can run this as a read-only review inside Claude, with each material result connected to the records and assumptions used.