Sales tax for interior designers, explained.

The moment an interior designer sells furniture to a client, the designer is a retailer in the eyes of most states, and retailers deal in sales tax. This is the part of the business nobody teaches in design school, so here is the whole loop in plain language: the resale certificate, what typically gets taxed, and the monthly discipline that keeps you out of trouble.

Why designers touch sales tax at all

If you buy a chandelier from a vendor and sell it to your client at a marked-up price, that final sale to the client is generally a taxable retail sale of goods. The design work is a service, and services are taxed differently (often not at all) depending on the state. It is the goods that make you a retailer.

The resale certificate loop

States do not want the same chandelier taxed twice. The mechanism that prevents it is the resale certificate: a registration that lets you buy inventory tax-free because you are going to resell it and collect the tax at the final sale.

Three things to notice. The tax you collect was never your money; it passes through you. The loop only works if the tax line actually appears on the client invoice for every resale-certificate purchase. And if you buy something tax-free on the certificate and then do not resell it (it goes in your own office, say), you generally owe use tax on it yourself.

Fees versus goods on the same invoice

Because services and goods are taxed differently in most states, keep them visibly separate: design fee lines and product lines that a state auditor could tell apart at a glance. Blending a fee into a product price does not just muddy your margins; in some states it can drag the whole blended amount into taxability.

Deposits and timing

Most small firms handle sales tax on a cash basis: the tax belongs to the period in which the invoice was actually paid, not the period you sent it. That means a deposit invoice paid in March carries its tax into March's filing even if the furniture arrives in June. Whatever convention your CPA sets, apply it consistently, and know which unpaid invoices are carrying tax you will owe the moment they are paid.

The monthly discipline

• A ledger that answers, per month: how much tax did we collect, on which invoices?
• A filing rhythm matched to your state's schedule (monthly, quarterly, or annual), with each filing recorded: amount, date, confirmation
• A watchlist for resale-certificate goods that were billed to a client with no tax line, because every one of those is your liability, not the client's
• Certificate housekeeping: renewals on time, and copies of the certificates your vendors have on file

The mistakes auditors find

They are always the same four: resale goods sold with no tax collected, certificate purchases kept for the studio with no use tax paid, fees and goods blended into single lines, and collected tax that sat in the operating account until it quietly became working capital. Every one of them is prevented by the loop above running monthly instead of at year-end.