Daily reality after launch
The printer fulfils orders, but the business is still yours to run. When a shirt arrives misprinted or two weeks late, the customer blames your store, not the supplier, so read the reprint and returns policy before you sell, and budget for the occasional refund. The ongoing work is uploading new designs, tweaking listings so your niche can find them, and answering customers. Expect weeks to months before the first steady sales; the sellers who get there treated the quiet period as testing time, not failure.
Copyright, trademarks, and account risk
Uploading fan art, brand logos, sports teams, or celebrity images is the fastest way to lose a print-on-demand account. Rights holders file takedowns constantly, and platforms suspend repeat offenders without much conversation. Stick to original work or designs you have properly licensed, and check each platform's intellectual-property and AI-art policies before you upload. A design that sells for a month and gets your account closed was never profitable.
Taxes and paperwork in the US
Income from print on demand is taxable from the first sale. The IRS treats online selling as reportable income even if no 1099 form is ever issued, so keep records of every payout and expense from day one. You do not need an LLC to start; a sole proprietorship is the default and works fine while you test. Sales tax depends on your state and on whether the marketplace collects it for you, so check the rules that fit your situation.