US sales tax — economic nexus, registrations, and resale certificates

The US has no federal sales tax. Each of the 45 states (plus DC) that collect sales tax sets its own rate, rules, and registration process. Sync handles the mechanics — per-state rates, shipping rules, resale certificates — but registration with each state Department of Revenue (DOR) is on you, since you are the seller of record on every order.

Economic nexus thresholds — when must I register?

Since the South Dakota v. Wayfair (2018) Supreme Court ruling, states can require remote sellers to register once they cross an in-state revenue or transaction threshold. The standard is $100,000 in annual sales OR 200 transactions in most states, but a few states are higher: California, Texas, and New York all use $500,000 (no transaction count). Track your in-state revenue per state — once you cross, you usually have 30–60 days to register before the state starts demanding back tax + penalties.

How to register

1. Visit the Department of Revenue website for each state where you have nexus (e.g. comptroller.texas.gov, cdtfa.ca.gov, tax.ny.gov).
2. For the 24 SST member states (AR, GA, IN, IA, KS, KY, MI, MN, NE, NV, NJ, NC, ND, OH, OK, RI, SD, TN, UT, VT, WA, WV, WI, WY), register once at streamlinedsalestax.org and pick a free Certified Service Provider (CSP) — the CSP will file returns for you in those 24 states at no charge.
3. Most states issue a permit number within 24–72 hours; some (CA, NY) take 1–2 weeks.
4. Add each state in Sync at Settings → Taxes → United States, then enter the permit number on the row.

Setting up the United States in Sync

1. Go to Settings → Taxes → United States.
2. Enable the federal toggle on the first card — this marks your business as US-registered and acts as the parent for all state registrations.
3. Click "+ State" and pick from the dropdown. Sync pre-loads each state's base rate (e.g. Texas 6.25%).
4. Enter your permit number for that state.
5. If your effective state + local rate differs from the base — e.g. NYC is 8.875%, not NY base 4% — enter a combined rate override.
6. Repeat for every state you have nexus in.

How tax is collected at checkout

• Buyer ships to a state you have a registration for: Sync charges your configured rate (override if set, otherwise base) on every taxable line.
• Buyer ships to a state you have NO registration for: Sync charges $0 sales tax. The order invoice prints a use-tax notice ("Sales tax not collected. Buyer may owe use tax in their state.") so the buyer is on notice.
• Buyer presents a resale certificate for the destination state: Sync zero-taxes the order and prints "Resale exempt — Cert #ABC-123" on the invoice in place of the tax line.

Resale certificates

When a wholesale buyer presents a state resale certificate (most common B2B case), store it on their customer record so future orders ship-to that state are zero-taxed automatically.

1. Open the customer in Customers → click their name.
2. Scroll to the "Resale certificates" sidebar panel.
3. Click + Add and fill in: state, certificate number, certificate type (state form, MTC uniform, SST, or multistate), exemption reason, and optional expiry date + uploaded PDF link.
4. On every future order shipping to that state, tax is zero-ed and the cert # prints on the invoice.
5. You can store multiple certificates per customer — one per state they're exempt in.

Use-tax notice on invoices

For orders shipping to a state you don't collect tax in, the order PDF includes a small italic footnote: "Sales tax not collected. Buyer may owe use tax in their state. Consult your state Department of Revenue." This is the buyer-protection language most states require non-collecting sellers to print on their invoices, and it shifts the use-tax obligation to the buyer.

Filing returns

Settings → Taxes → "Tax report" downloads a CSV of tax collected per state for any given month. For SST states, your free CSP files for you. For non-SST states (CA, TX, FL, NY, IL, PA, etc.), you file directly with each state on their cycle (monthly, quarterly, or annual depending on volume).

Marketplace facilitator note

Sync is software, not a marketplace. Unlike Amazon, eBay, or Walmart Marketplace — which collect and remit sales tax on behalf of their sellers under Marketplace Facilitator laws — you remain the seller of record on every Sync order, and registering with each state where you have nexus is your responsibility. This is the same model Shopify and BigCommerce use.