Sales Tax Nexus After Wayfair: The 6 States That Cost DTC Brands the Most

The 2018 South Dakota v. Wayfair Supreme Court decision should have been the wake-up call. Instead, six years later, the most common ecommerce financial disaster I see is still the same: a $2-15M brand discovers it has economic nexus in 18 states, has been collecting sales tax in two of them, and is staring at $40K-$300K in back tax, penalties, and interest.

This post is the practical guide every Shopify and Amazon seller should have read three years ago.

What economic nexus actually means

Before Wayfair, you only had to collect sales tax in states where you had physical presence (a warehouse, office, or employee). After Wayfair, every state can require you to collect sales tax based on economic activity — typically:

• Annual sales above a threshold (commonly $100K), OR
• Number of transactions above a threshold (commonly 200)

Each state sets its own threshold. Each state has its own forms. Each state has its own filing frequency. There are roughly 45 sales-tax states + DC. That's the compliance burden.

"I'm baffled as to how you report that on the sales tax return. I've even asked a bookkeeper who does sales tax filings for several businesses, and she doesn't know either. I'm stumped." — drop-shipper, r/ecommerce

The bookkeeper isn't incompetent. The system is genuinely complex.

The 6 states that cause the most damage

Not all states are created equal. These six are where I see the most expensive surprises:

1. California

• Threshold: $500K in sales (no transaction count)
• Why it hurts: Highest combined rates (up to 10.75%), aggressive enforcement, district-level rate complexity
• Common trap: Shopify charges flat 7.25% (state base rate) but actual rates vary by ZIP — under-collection is your liability

2. New York

• Threshold: $500K in sales AND 100 transactions
• Why it hurts: Marketplace facilitator law shifts liability to Amazon/Etsy/eBay, but DTC sales through your own site stay yours; clothing exemption rules are byzantine
• Common trap: Mixing marketplace and DTC sales in your books, then under-remitting

3. Washington

• Threshold: $100K (low!)
• Why it hurts: Combines retail sales tax + B&O (Business & Occupation) tax, which is on gross receipts even at zero margin
• Common trap: Forgetting B&O tax entirely — it's an income tax in everything but name

4. Texas

• Threshold: $500K
• Why it hurts: Aggressive nexus enforcement, sophisticated audit teams, no income tax means sales tax is the primary state revenue
• Common trap: Drop-shipping into Texas while based elsewhere — Texas considers you nexus-creating

5. Florida

• Threshold: $100K (added in 2021, so older brands often missed retroactive enforcement)
• Why it hurts: Many sellers thought they were exempt because Florida was late to economic nexus; back-collection assessments are now common
• Common trap: Assuming "we don't have nexus in Florida" when you crossed the threshold three years ago

6. Colorado

• Threshold: $100K
• Why it hurts: Home-rule cities (Denver, Boulder, Colorado Springs, etc.) require separate local registrations and filings — not handled by the state
• Common trap: Registering with Colorado Department of Revenue and thinking you're done; you're not

The marketplace facilitator double-count trap

Here's a real case from r/Bookkeeping that I've personally seen variations of multiple times:

"TaxJar acknowledges that these exports do NOT account for the sales tax payments that marketplaces like Amazon make due to marketplace facilitator laws. So what happens is we'll get an export from TaxJar that says 'here is a bill for the $100 in sales tax you owe to California for April 2021 sales,' but meanwhile Amazon has already collected and remitted that $100 to California."

Marketplace facilitator laws (now in effect in 47 states) shift the collection and remittance obligation for marketplace sales to the marketplace itself (Amazon, Etsy, Walmart, eBay). The seller is no longer the responsible party for those transactions.

The trap: if your books treat all sales identically, you double-count. You record:

1. Gross sales including sales tax that Amazon collected and remitted
2. Sales tax liability for those same sales
3. Then your sales tax software bills you again for the tax you don't actually owe

The fix is to separate marketplace sales (where the platform handles tax) from direct sales (where you handle tax) at the GL level. This is fundamental ecommerce accounting that most general bookkeepers get wrong.

Drop-ship complications

If you drop-ship — meaning your supplier ships directly to your customer — you have a special wrinkle. Two transactions are happening:

1. You sell the product to the customer (taxable to your customer's location)
2. Your supplier sells the product to you (taxable in supplier's state, unless you provide a resale certificate)

"We have been battling sales tax exemptions for years as a reseller that dropships nationally. All sales taxed we are charged is a loss and if we do incorporate it into our price it will deem us noncompetitive on price." — drop-shipper, r/ecommerce

The fix is resale certificates for every state where your supplier might charge you sales tax. The Uniform Sales & Use Tax Resale Certificate (Multi-Jurisdiction) is accepted by 36 states and is the place to start. The remaining states require state-specific forms.

If you're paying sales tax to your supplier and then collecting sales tax from your customer, you're double-paying — and you can usually claim a refund or credit, but it requires meticulous documentation.

What it actually costs to comply

For a $2-10M DTC brand selling in all 50 states:

For comparison, the cost of not complying — discovering 4 years of unfiled returns in a state where you have nexus:

A $5M brand with 4 years of un-filed Texas sales tax could easily face $200K+ in exposure.

The defensible compliance approach

For a growing DTC brand, here's what I recommend:

Phase 1: Nexus study (do this first)

Hire a sales tax specialist (or use a service like TaxJar/Avalara/Anrok) to map your nexus footprint. You're looking for:

• Every state where you've crossed the economic nexus threshold
• Every state where you have physical nexus (warehouses, FBA inventory, employees)
• Every state where your suppliers create nexus through drop-ship

Phase 2: Voluntary disclosure where you're behind

For states where you have nexus but never registered, voluntary disclosure agreements (VDAs) are typically your best move. States want compliance and will:

• Limit the look-back period (usually 3-4 years)
• Waive most or all penalties
• Sometimes reduce interest

Do this before the state finds you. Once you receive a notice, the deal gets worse.

Phase 3: Get current and stay current

Register in every nexus state. Configure Shopify/Amazon/Etsy to collect correctly. Use sales tax software for filings. Reconcile sales tax liability monthly.

Phase 4: Monitor for new nexus

Every quarter, re-check your sales by state against thresholds. Crossing into a new state mid-year still triggers nexus — you just need to register and start collecting from that point forward.

What good ecommerce bookkeeping looks like for sales tax

Three things separate clean from chaotic books on this front:

1. Marketplace vs. DTC sales are tracked separately — different revenue accounts or separate "class" tags
2. Sales tax liability is a real GL account with monthly reconciliation to filings
3. State registrations are documented in a single tracker the bookkeeper, CPA, and CFO all reference

If your bookkeeper can't show you: a state-by-state liability report, marketplace vs. DTC split, and a list of where you're registered — you're flying blind.

When to call Level

We don't file sales tax returns directly — that's specialized work for tools like Avalara, TaxJar, or Anrok. But we do scope and oversee the entire sales tax compliance posture as part of CFO engagements with growing DTC brands. That includes nexus studies, VDA decisions, software selection, and the ongoing monthly reconciliation that keeps the system honest.

FAQ

Does Shopify automatically handle sales tax? No. Shopify can calculate sales tax based on the destination, but you have to configure it correctly, register in each state, and file the returns yourself. Shopify Tax (the new product) helps with rate calculation but doesn't file for you.

What if I only sell on Amazon FBA? For FBA, Amazon collects and remits sales tax in all 47 marketplace facilitator states. Your direct nexus exposure is much lower — but you still need to verify FBA inventory locations create physical nexus and that you're not required to file informational returns in some states.

How far back can a state assess back sales tax? Statute of limitations varies by state, but most are 3-4 years from filing date. Critically: if you never filed, the statute never starts. Some states will look back 7+ years if they discover you had nexus and never registered.

My bookkeeper says we're "fine" because Shopify charges tax. Is that true? Shopify charging tax doesn't mean it's being remitted. You need to verify: (1) you're registered in every nexus state, (2) Shopify is configured to charge correctly, (3) you (or your sales tax software) are actually filing the returns and remitting the money. Many sellers collect tax for years and never file.

Related reading:

• Why Your 1099-K Doesn't Match Seller Central
• Marketplace Facilitator Sales Tax in QuickBooks
• Ecommerce Bookkeeping That Actually Works