Sales tax basics US startups should know

Sales tax basics startups need are narrower than a full tax course: know where you might owe, register before you collect, file on time, and keep the rate you print on invoices tied to advice you can defend. Nautis does not decide nexus or file returns. Invoices can store a Tax Name and Tax Rate on the summary when you already know what to charge. This is operating orientation for US founders, not tax, legal, or accounting advice. Confirm every trigger and rate with a CPA or sales-tax specialist before you collect or remit.

Sales tax basics startups should sort from other taxes

Sales tax is usually a state and local tax on taxable sales of goods or certain services, collected from the buyer and remitted by the seller when the seller has a required connection to that place. Income tax, payroll tax, and VAT-style regimes are different problems. Do not mix them on one sticky note.

Founders also confuse sales tax with a fee they may keep. Collected tax is money you hold for a government. Parking it in runway math or paying operating bills with it creates a hole when the return is due. Keep remittance cash visible in the business account you already use for company funds.

Sales tax basics startups should lock early:

1. Where you have nexus (a connection that can create a duty to register).
2. What you sell that is taxable there.
3. Whether marketplace facilitators already collect on some channels.
4. How you will show Tax Name and Tax Rate on customer invoices once counsel or your CPA signs off.

Illustrative mix-up (composite only): a team treated payment-dashboard tax toggles as a full compliance program, collected in two states, and never registered. The fix cost more than a CPA hour would have on day one.

Nexus after Wayfair, without memorizing every state chart

On June 21, 2018, the US Supreme Court held in South Dakota v. Wayfair that states may require sellers to collect and remit sales or use tax on sales delivered into the state even when the seller has no physical presence there. The Streamlined Sales Tax Governing Board summarizes the same holding for remote sellers.

Physical presence still matters. Streamlined guidance states that if you have a physical presence in a state, you are not treated as a remote seller for that state's economic-nexus rules and you generally must check that state's registration rules regardless of sales volume. Economic nexus is the additional path many states use for sellers without physical presence: if your sales or transaction counts into a state meet that state's threshold, you may have to register and collect.

Do not invent a single national dollar cutover. Streamlined's remote-seller state guidance explains that thresholds vary: some states use sales or transactions, some use both, and sales may be measured as gross sales, retail sales, taxable sales, or similar terms that are not interchangeable. Use that chart and each state's revenue site with your CPA. Thresholds and compliance dates change; treat any blog table as a pointer, not the law.

Keep the board in a dated Note. Update it when you hire remote, add a 3PL, or cross a revenue band your CPA flagged. Silent changes (one hire, one pallet) are the usual miss.

What not to put on the board

Do not list every local rate by hand on day one. Do not copy a competitor's invoice rate. Do not treat "we only sell software" as a free pass: digital and SaaS taxability depends on state law and how your offer is classified. Ask your CPA; do not paste rates from social posts.

Register, collect, file: the order that keeps you out of cleanup

Sequence matters.

1. Advisor review of the nexus board against Wayfair-era remote-seller rules and physical-presence facts.
2. Registration in states where you must register, with account numbers stored where finance can find them. Streamlined member states allow one Streamlined Sales Tax Registration System application for those states; non-member states need each state's own registration path.
3. Only then collect tax on channels you control, using rates your advisor approved.
4. File and remit on that state's calendar, including periods where the amount due is zero if the state still requires a return.

Collecting before registration is a common self-inflicted wound. So is registering, collecting, and then missing filings.

Assign one human owner for the filing calendar. Put return due dates next to payroll dates so they stay visible when cash feels tight.

Illustrative order (composite only): home-state registration before taxable direct sales, quarterly economic-nexus review against advisor-confirmed thresholds, marketplace channel left on facilitator collection where the platform is responsible, direct website invoices showing Tax Name and Tax Rate only after the CPA memo lands.

Marketplace versus direct

Many states require marketplace facilitators that meet their rules to collect and remit on sales they facilitate for third-party sellers. Streamlined publishes marketplace-facilitator state guidance and warns that definitions and duties still vary by state. Facilitator collection on one channel does not automatically cover your own checkout, contracts, or manual payment links. Split reporting so you do not double-collect or under-collect on the direct slice. Marketplace sellers can still have their own registration questions; confirm with your CPA.

Put the agreed rate on invoices without inventing a tax engine

When your advisor has named the rate for a given customer location and product, you may set Tax Name and Tax Rate (%) on the invoice summary in Invoices. Those fields apply to the subtotal. They are not a nexus checker, rate database, or filing product.

Rules of thumb for the ops owner:

• Change Tax Name and Tax Rate only from a written advisor note, not from a Slack guess.
• If a customer is exempt, store the exemption proof outside the invoice PDF and follow the exemption process your CPA describes.
• Recurring invoices inherit whatever you set; revisit them when rates or destinations change.

Nautis will not tell you whether a SaaS SKU is taxable in a given state. If the team cannot point to a memo, leave Tax Rate at zero and finish the advice before you start collecting.

Product catalog hygiene helps: when you add a product or service in Invoices, keep the description aligned with what the CPA classified. Ops renaming SKUs in chat without updating that record is how the wrong Tax Rate gets pasted later.

For cash timing after invoices send, keep burn math honest with How to calculate startup burn rate and runway. Sales tax you collect is not revenue; do not celebrate it as MRR.

A monthly operating loop (not a substitute for filings)

Escalate to the CPA when a board row flips to yes, when a customer disputes tax, or when you enter a state for the first time. Do not wait for year-end.

Customer disputes need a paper path: who replies, whether collection pauses, and whether you issue a credit note after the CPA agrees. Do not quietly delete invoices to make a tax argument disappear.

Illustrative loop (composite only): week 1 notes a new contractor living in another state; the same day the founder emails the CPA; collection into that state stays off until the reply; invoices keep Tax Rate empty rather than guessed.

Illustrative first year at Northline Goods

Illustrative Northline Goods (composite only): ships physical accessories from one US warehouse, sells on their site and one marketplace.

Quarter 1: register where physical presence and home-state rules require it; marketplace facilitator handles that channel under applicable facilitator rules; site invoices use Tax Name and Tax Rate from the CPA sheet only for destinations the memo covers. Quarter 2: economic-nexus review against advisor-confirmed thresholds from state guidance; still under; no new registrations. Quarter 3: add a 3PL bin in a second state; board row flips; CPA confirms registration before peak season. Quarter 4: filings stay on calendar; ops never uses collected tax to pad runway slides.

They never built a custom tax engine inside the CRM. Sales tax basics startups actually need were the board, the register-then-collect order, and invoice fields that only mirrored advice.

When peak season hit, the 3PL state was already registered, so they did not freeze checkout to scramble paperwork. Northline still reviews the nexus board when they add a wholesale channel. Any exemption process runs through the CPA before anyone types a zero into Tax Rate on a hunch.

What to take to counsel and your CPA

Bring the nexus board, last three months of sales by state if you have them, a sample invoice PDF, a list of channels (direct, marketplace, live events), and where inventory sits. Ask what to register, what is taxable for your SKUs, what facilitators already cover, and how often to reassess. Point them at Streamlined remote-seller and marketplace-facilitator guidance as a starting map, then follow each state's site.

Nautis Expenses, Startup Health, and Invoices will not replace that meeting. Until the memo exists, treat social-media "sales tax basics startups" threads as prompts for questions, not as rates to paste into Tax Rate.