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Selling online in the US: platforms and rules explained

By FastBuySale Newsroom · 9 Nov 2026 · 21m ago

Who this guide is for

Selling online in the US can mean clearing out a closet, running a part-time side business or building a full online brand. The channel you choose and the rules that apply change with your scale. This explainer covers the main platform types, the federal rules that apply to online sellers and the tax basics, using FTC and IRS guidance. It does not promise any income; results depend on what you sell, pricing, competition and effort. State laws vary, so check your own state's requirements too.

Step 1: choose your channel

General online marketplaces. Large audiences and built-in payment and trust systems. You pay selling fees, follow the marketplace's policies and compete directly with many sellers.

Niche marketplaces. Platforms for fashion, handmade goods, electronics, books, collectibles or furniture. Audiences are smaller but more targeted.

Social selling and local listings. Selling through social networks, community groups and local classified sites. Fees can be low or zero, but you handle more of the payment safety and meeting logistics yourself.

Your own online store. Hosted e-commerce tools let you run a store under your own brand. You control the customer relationship and pricing, but you must bring your own traffic and handle sales tax, payments, policies and customer service.

Many sellers combine channels, for example a marketplace for discovery and their own store for repeat customers.

Step 2: work out your real margin

Selling fees are only part of the cost. Add payment processing, shipping labels, packaging, returns, advertising and the value of your time. A simple worked example:

A seller lists a refurbished lamp at 80 dollars. Platform and payment fees total 13 percent, or 10.40 dollars. Shipping and packaging cost 14 dollars, paid by the seller to offer free shipping. The lamp cost 30 dollars to buy and 6 dollars in parts. Profit is 80 - 10.40 - 14 - 36 = 19.60 dollars before tax and before the seller's time. If one in ten orders is returned at the seller's cost, the average profit falls further. The percentage calculator linked on this page helps you test different prices and fee levels.

Step 3: follow the FTC's shipping rule

The FTC's rule on goods ordered by mail, phone or online, usually shortened to the Mail Order Rule, applies to most online sales. You must have a reasonable basis for any shipping time you state. If you do not state a time, you must ship within 30 days. If you cannot ship on time, you must notify the buyer, give a revised date and offer the option to cancel for a prompt refund. Delays happen; ignoring them is what creates legal problems and bad reviews.

Step 4: understand sales tax

Since the Supreme Court's 2018 decision in South Dakota v. Wayfair, states can require remote sellers to collect sales tax once they pass economic nexus thresholds, often based on sales value or number of transactions in the state. Every state with a general sales tax also has a marketplace facilitator law, which makes large marketplaces collect and remit tax on sales made through them. If you sell only through such marketplaces, you may not need to collect tax yourself for those sales, but some states still require registration. If you sell through your own website, you are generally responsible for registering, collecting and filing in each state where you have nexus.

Step 5: know the INFORM Consumers Act

Since 27 June 2023, the INFORM Consumers Act has required online marketplaces to collect and verify bank account, contact and tax identification information from high-volume third-party sellers, meaning sellers with 200 or more discrete sales and 5,000 dollars or more in gross revenue in a continuous 12-month period during the previous 24 months. Sellers with 20,000 dollars or more in annual gross revenue on a platform must also make certain identity and contact details available to buyers. Marketplaces must suspend sellers who do not comply. The FTC and state attorneys general enforce the law.

Step 6: list honestly and handle reviews properly

Describe condition accurately, disclose flaws, use your own photos and state your return policy clearly. The FTC's rule on consumer reviews and testimonials prohibits fake reviews, buying positive reviews and suppressing negative ones, among other practices. Offering an incentive in exchange for a positive review is not allowed. Responding to criticism politely and fixing problems builds trust far more than any shortcut.

Step 7: check product safety and restricted items

Some products have extra rules. Children's products generally require testing and a Children's Product Certificate under Consumer Product Safety Commission rules. Recalled products must not be resold. Cosmetics, supplements, food, firearms parts, hazardous materials and items using brand names you do not own can all carry legal and platform restrictions. Check both the law and each platform's prohibited items list before listing.

Step 8: get the tax basics right

Selling personal items for less than you originally paid generally produces no taxable gain. Selling at a profit, or buying goods to resell, creates taxable income. Regular sellers who sell with a profit motive usually report income and expenses on Schedule C and may owe self-employment tax on net earnings of 400 dollars or more.

For 2026, payment platforms and marketplaces must send Form 1099-K when a seller's payments exceed 20,000 dollars and 200 transactions in the year. The form is an information return; it does not decide what is taxable. Keep records of what each item cost you, the sale price and expenses such as fees and shipping so you can show your actual profit.

Step 9: protect yourself from scams

Common seller scams include fake payment confirmation emails, buyers asking to pay outside the platform, overpayment with a request to refund the difference, and claims that an item never arrived when tracking shows delivery. Keep transactions inside the platform's payment system, ship only to the address on the order, use tracked shipping and keep proof of postage.

Step 10: set clear return and refund policies

Federal law does not require a general right to return goods bought online, but platforms often set minimum return standards, and some states require retailers to post their refund policy clearly or apply a default policy if they do not. Write down what you accept back, how many days buyers have, who pays return shipping and how quickly refunds are issued. Apply the policy consistently. If a buyer disputes a card payment, clear policies, tracking numbers and messages showing what was agreed are your best evidence.

Step 11: register the business when it grows

Casual sellers rarely need formal registration, but once you sell regularly you may need a business name registration if you trade under a name other than your own, a local business licence and a sales tax permit. An employer identification number from the IRS is free and lets you avoid sharing your Social Security number with suppliers. Separate business and personal bank accounts simplify bookkeeping and tax time.

Worked example: choosing a channel

Mia makes ceramic mugs at home and sells about 30 a month. She starts on a handmade marketplace for discovery, where fees are a percentage of each sale and tax is collected by the marketplace. After a year, repeat customers ask to buy directly, so she opens a small online store. She registers for sales tax in her home state, checks whether she meets nexus thresholds elsewhere and adds clear shipping times to her product pages to stay within the FTC's rule.

Printable checklist

Channel: marketplace, niche site, social selling, own store or a mix?

Margin: price minus fees, shipping, packaging, returns and cost of goods?

Shipping: stated times realistic; process for notifying delays and offering cancellation?

Sales tax: marketplace collecting, or do I need to register and collect myself?

INFORM Act: am I a high-volume seller, and is my information verified?

Listings: accurate descriptions, real photos, clear returns, no incentivised reviews?

Products: any safety rules, recalls or restricted categories?

Tax: records of cost and sale price; Schedule C and self-employment tax if a business?

The bottom line

Selling online in the US is accessible to almost anyone, but it comes with real rules once you sell regularly. Choose a channel that fits your products, price for every cost, state realistic shipping times and keep careful records. Use the FTC's business guidance and the IRS small business pages as your official references, and check your state's tax and licensing rules. This guide is general information and does not promise any income.

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