Rules
A US sales tax nexus checklist after Wayfair for ecommerce acquisition
Wayfair sales tax nexus ecommerce customer acquisition cost: how thresholds, storage rules and registration duties reshape pricing and paid channels.
What to take away
- Wayfair sales tax nexus ecommerce customer acquisition cost is now a pricing input: a single economic threshold can add six figures of annual collection and filing work that never appeared in your ad budget.
- Most states trigger economic nexus on a sales amount, a transaction count, or both, and the count usually arrives first for low-ticket stores.
- Storing inventory in a third-party fulfillment center in another state creates physical nexus there, even when your office, staff and bank account stay home.
- Marketplace facilitator rules shift collection to Amazon, Etsy, Walmart and similar platforms for sales they process, but not for your own website or your income tax filing.
- Registration, back filing and voluntary disclosure cost money that competes directly with the budget you would otherwise spend on paid acquisition.
- Check each state tax authority directly before you scale spend into a new region, because thresholds and marketplace rules change every legislative session.
What Wayfair changed for ecommerce sales tax nexus
The Wayfair decision, South Dakota v. Wayfair, Inc., decided in 2018, removed the physical presence requirement that had shielded remote sellers since 1992. Before it, a warehouse, office or sales force in a state was normally needed before that state could require you to collect. After it, a state can require collection based on economic activity alone.
The practical effect is that growth itself creates tax obligations. Every new state you ship into, every new fulfillment center you rent, and every affiliate or contractor you sign can add a filing calendar. A store that sold into 12 states in 2019 might now be registered in 30.
This is not a federal system. There is no national sales tax registration. Each state writes its own threshold, its own tax base, its own filing frequency and its own penalty schedule.
The Internal Revenue Service administers federal income tax, not sales tax, so its role here is limited to business registration and federal compliance context through the IRS businesses hub.
For founders, the first consequence is administrative, not financial. You need a map of where you have customers, where you have inventory, and where you have people. Those three maps rarely overlap, and the union of them is your nexus footprint.
Economic nexus thresholds by state and what they trigger
Economic nexus thresholds are the sales or transaction levels that let a state require collection from a remote seller. They vary widely, and the differences matter more than the headline numbers suggest.
Show the numbers
| California | $500,000 |
|---|---|
| New York | $500,000 |
| Texas | $500,000 |
| Illinois | $100,000 |
| Washington | $100,000 |
| Colorado | $100,000 |
| Massachusetts | $100,000 |
| Florida | $100,000 |
Two lessons sit in that table. First, a $100,000 threshold in Illinois, Washington, Colorado, Massachusetts or Florida can be crossed by a modest store in a single quarter. Second, states with a transaction test, such as New York, can pull in sellers whose revenue is well below the dollar figure.
Thresholds are usually measured on the previous or current calendar year, depending on the state. Some count gross sales including exempt and wholesale sales, others count only retail. Some include marketplace sales in the total, which can push a seller over a threshold even though the marketplace collects the tax.
Once crossed, the obligation normally starts on a defined future date, not retroactively, though states have pursued back tax in audits. The trigger is not a bill. It is a duty to register, collect, file and remit, whether or not you have collected anything from customers.
Inventory storage and marketplace facilitator rules
Inventory storage rules are the physical half of nexus, and they surprise founders who assume remote selling means remote everything. If your inventory sits in a third-party fulfillment center, a 3PL warehouse, or a consignment location in a state, that state generally treats you as physically present.
That applies even when the fulfillment provider is a marketplace. Amazon FBA inventory in a Pennsylvania or Texas warehouse can create physical nexus in those states regardless of your sales volume there. The same logic covers a small storage unit used for returns processing.
Marketplace facilitator rules are the counterweight. States now require large platforms to collect and remit sales tax on sales they process, which shifts the collection duty to Amazon, Etsy, eBay, Walmart Marketplace and similar operators for those transactions. That relieves sellers of collection on marketplace orders in most states.
It does not relieve sellers of everything. Marketplace sales often still count toward economic nexus thresholds, so a seller can cross a state's limit on marketplace volume alone and then owe collection on its own website sales into that state. Income tax nexus, business licenses and annual reports are separate questions the facilitator rules do not answer.
For a startup mixing channels, this creates an odd pattern: the channel doing the collecting may be the one creating the obligation on the channel that is not.
Registration duties once a threshold is crossed
Registration duties begin the moment a state considers you a taxpayer, and they are more than a form. You apply for a sales tax permit, appoint a contact, choose a filing frequency, and start collecting on taxable sales from the effective date.
- Confirm the trigger date and the state's measurement period, so you know which sales are taxable.
- Register for a sales tax permit with the state tax authority, using your federal employer identification number where the application asks for it. If you do not have one, the IRS page on getting an employer identification number explains how to apply at no cost.
- Set up collection in your store platform, including taxability rules for shipping, digital goods, clothing and food, which differ by state.
- File the first return on the assigned schedule, monthly, quarterly or annually, even if the return is zero.
- Keep exemption certificates from resellers and wholesale customers, because without them those sales can be assessed as taxable.
Filing frequency is assigned by the state based on expected liability. High-volume sellers file monthly, which means twelve returns a year per state. Ten states is 120 returns, plus local returns in states such as Colorado where home rule cities administer their own taxes.
Penalties accrue for late registration and late payment, and some states publish names of delinquent taxpayers. Voluntary disclosure programs exist for sellers who missed a threshold, and they usually reduce penalties in exchange for back filing a limited number of years.
If you are still setting up the business itself, the IRS guide to starting a business covers the federal steps that come before state sales tax registration, including entity choice and the EIN.
How nexus changes pricing and acquisition math
Nexus changes unit economics, and unit economics decide how much you can pay to acquire a customer. That is why this belongs in the same spreadsheet as your customer acquisition cost by channel, not in a separate compliance folder.
Start with the direct costs. Registration fees are small, often under $100 per state. The real cost is labor: bookkeeping, filing software, and professional review. A store filing in 20 states can spend five figures a year on compliance before a single return is audited.
Then add the pricing effect. If you sell into a state where you must collect tax and your competitor on a marketplace does not show it at checkout, your displayed price looks higher. Conversion drops, and the same ad spend buys fewer customers.
That is a real increase in effective acquisition cost even when the ad platform reports the same cost per click.
Finally, consider collection timing. Sales tax collected is not your money. It sits as a liability until remitted, and treating it as working capital is how founders end up short at filing time. Budgeting for that float is part of the same cash plan that funds campaigns.
Teams that map this early can also use it. A state with a high threshold and no transaction test is cheaper to enter than one with a low threshold and a 200-transaction trigger, so channel and geo decisions can be sequenced around compliance cost rather than after it.
State tax authority research before scaling ad spend
The state tax authority is the only source that settles a nexus question. Marketing blogs, agency posts and platform help centers lag behind legislation, often by years. Before you commit budget to a new region, read the primary source.
The IRS maintains a directory of state government websites that links to each state's tax agency, which is the fastest route to the correct authority rather than a third-party summary.
California is a useful example of why the detail matters. The California Department of Tax and Fee Administration explains use tax obligations for out-of-state retailers, including the rules that apply when a remote seller has no physical presence but crosses the economic threshold.
Build a one-page sheet per state with four fields: threshold and measurement period, whether marketplace sales count, registration deadline, and filing frequency. That sheet becomes the input to your media plan, not a document you write after the campaign.
Timing matters too. Several states have changed thresholds and marketplace rules since 2023, and legislative sessions run annually. A state profile written two years ago may be wrong today. Recheck before each major spend increase, especially before a seasonal push.
The same discipline applies to benchmark setting. A startup customer acquisition costs in canada that assumes one national tax treatment will misprice every state where you collect and every state where you do not.
A nexus checklist to run before the next campaign
Run this before you increase budget into a new state or add a new fulfillment location. It takes an afternoon and prevents a filing backlog.
- Pull a state-by-state sales report for the trailing 12 months, separating marketplace orders from your own website orders.
- List every location where you or a contractor stores inventory, including 3PL, FBA and returns processing sites.
- List every state where you have an employee, contractor or affiliate relationship that could create physical presence.
- Compare each state's economic nexus threshold against your figures, using both the sales test and the transaction test.
- Check whether marketplace facilitator rules cover each channel you sell through in that state.
- Confirm registration status and filing frequency for every state where you are already registered.
- Get the current threshold and filing rules from the state tax authority, not from a summary post.
Once the checklist is done, feed the results into your common startup market research questions and your state-by-state spend plan. The states where you collect tax may need a different price test, a different offer, or a different channel mix.
Then revisit the numbers you use to judge performance. A rising effective cost per acquisition is sometimes a tax story, not a creative story, and knowing which one you are looking at prevents you from cutting spend that is still working.
Teams looking to reduce startup customer acquisition cost should start here, because state tax treatment is one of the few cost lines a founder can plan around rather than simply absorb.
Two habits keep this manageable. First, review nexus quarterly alongside your channel review, so new states surface before they become back filings. Second, keep the compliance cost visible in the same dashboard as ad spend, because both come out of the same bank account and both affect how much growth you can afford.
Founders who treat nexus as a finance task separate from growth often discover it during an audit, when the cheapest options are gone. Founders who treat it as a channel input make better state-by-state decisions and avoid the surprise invoice.
Common questions
Does selling on Amazon mean I have no sales tax obligations? No. Marketplace facilitator rules make Amazon collect and remit on sales it processes, but your marketplace volume can still push you over a state's economic nexus threshold, which then applies to your own website sales into that state.
Do I owe tax in a state where I only store inventory? Generally yes. Inventory storage rules treat a third-party fulfillment center or warehouse in a state as physical presence, which creates nexus regardless of how much you sell there.
What happens if I cross a threshold and do nothing? The state can assess back tax, interest and penalties for the period you should have been collecting, and some states publish delinquent taxpayer lists. Voluntary disclosure programs can reduce penalties but usually require back filing.
Do I need an employer identification number before registering for sales tax? Most state applications ask for a federal employer identification number, and the IRS issues one at no cost. Sole proprietors without employees may use a Social Security number in some states, but an EIN keeps business and personal identity separate.
How often do thresholds change? Frequently. State legislatures adjust sales thresholds, transaction tests and marketplace rules on their own schedules, so a profile written a few years ago can be out of date. Check the state tax authority before each major spend increase.
Should compliance cost change my ad budget? It should change your planning, not necessarily your total budget. Higher effective cost per acquisition in collect states may justify shifting spend toward states or channels where the math still works, rather than cutting volume outright. Founders weighing that tradeoff against channel performance can compare notes on community-led acquisition versus paid ads before committing the next quarter's budget.
