A Year-Round Bookkeeping Checklist for Marketplace Sellers

Year-end reporting is much easier when a seller's records have been maintained throughout the year. Waiting for a payment processor form does not recreate inventory costs, cash sales, refunds, shipping, marketplace fees, owner activity, or business expenses that occurred outside the processor.

This article provides general educational bookkeeping information, not tax, payroll, legal, or worker-classification advice. Requirements can vary by year, business, worker, payment method, and jurisdiction. Verify current rules with the IRS, applicable agencies, and qualified professionals.

Separate the business activity

Use dedicated business bank and card accounts and keep each marketplace and payment processor identifiable. Avoid mixing personal transfers and purchases into business sales. When owner funds enter or leave the business, record them according to the entity and transaction rather than disguising them as revenue or expense.

Record gross activity—not only deposits

A processor payout is a net settlement. It may combine customer payments, refunds, disputes, processing fees, reserves, adjustments, and several days of transactions. Record the underlying components and treat the transfer to the bank as a transfer, not a second sale.

Reconcile every sales channel monthly

Compare marketplace and processor reports with the books and bank deposits. Confirm beginning balance, gross charges, refunds, disputes, fees, adjustments, payouts, and ending or pending balance. Investigate missing, duplicated, or delayed activity while the details are recent.

Track inventory and product costs

Purchasing merchandise is not the same as selling it. Maintain records for quantities and costs, including production, freight, damaged goods, samples, returns, and items still on hand. Use a method appropriate to the business and obtain tax guidance for inventory and cost-of-goods-sold treatment.

Preserve receipts and business purpose

Save invoices, receipts, contracts, shipping records, subscription statements, and proof of business purpose. Bank data may show the vendor and amount but not what was purchased, whether it was partly personal, or whether it belongs to equipment, inventory, supplies, or another category.

Keep sales tax visible

Separate product revenue, shipping, discounts, refunds, and tax amounts in the records. Determine whether the marketplace, seller, or another party collected and remitted the tax. Marketplace-facilitator treatment and seller responsibilities vary, so bookkeeping records should preserve the detail needed for the applicable filings.

Review contractors and payroll

Collect worker and vendor information before payment and distinguish employees from nonemployees using the applicable rules. Track payment method because card and qualifying third-party network payments may be reported by the settlement entity rather than on Form 1099-NEC.

Complete a quarterly health check

Review profit and loss, balance sheet, cash, outstanding customer balances, bills, debt, inventory, payroll liabilities, and sales-tax records. Compare actual results with the seller's expectations and prepare for the next busy or slow period.

Prepare before year-end

• Confirm legal name, address, and taxpayer identification information on each payment account.
• Finish monthly reconciliations and resolve unidentified transactions.
• Review inventory, unpaid bills, refunds, disputes, loans, and owner activity.
• Check contractor records and payment methods.
• Download year-to-date processor and marketplace reports.
• Compare information forms with the books rather than replacing the books with the forms.

Make bookkeeping part of selling

Consistent records help marketplace sellers understand margins, prepare for obligations, and respond when a processor form arrives. Contari Bookkeeping Services can organize catch-up activity or maintain a monthly process that keeps sales channels, expenses, inventory, and year-end records working together.

Official references

IRS: Understanding Your Form 1099-K
Stripe: How to Select a Financial Report