What Brick-and-Mortar Retailers Need to Know Before Selling Online

Estimated reading time: 12 minutes

Sales Tax Compliance

Adding an online channel doesn't just expand your market — it fundamentally changes your sales tax obligations. What worked for in-store transactions doesn't automatically translate online.

🏪 Audience: Brick-and-Mortar Retailers 🛒 Topic: Ecommerce Tax Compliance 🗺️ Coverage: Multi-State Sellers

Your existing nexus Economic nexus Certificates go digital Common mistakes Setup checklist Consequences FAQs

What You'll Learn

Why you already have nexus in your store states and what that means for online sales
How online orders trigger new economic nexus obligations in other states
The difference between in-store and online exemption certificate management
Common mistakes retailers make when launching ecommerce
How to set up tax collection correctly from day one

You've run a successful retail business for years. You understand sales tax in your store states. You collect exemption certificates from business customers. Everything works. Then you launch a website. Suddenly, orders come from everywhere. Business buyers ask how to submit exemption certificates online. And you're wondering: do I charge sales tax on these orders?

The answer is more complex than most retailers expect. Here's what you need to know before your first online order ships.

You Already Have Nexus (And What That Means)

If you have physical stores, you already have nexus in those states. That hasn't changed. Online orders to customers in your store states are taxable from day one — no new registration needed.

What does change is how tax is calculated. Most states use destination-based sourcing for online sales. The shipping address determines the tax rate, not your store location. Your ecommerce platform needs to apply the correct rate for the customer's zip code — not a flat state rate.

Example: You have stores in Illinois, Wisconsin, and Indiana. An online customer in Chicago needs the correct Chicago city rate applied — not just Illinois state rate. An online customer in the suburbs needs a different rate entirely. Destination-based sourcing is not optional.

Economic Nexus: The New Rules That Change Everything

After South Dakota v. Wayfair (2018), states can require remote sellers to collect tax based on sales volume alone — no physical presence needed. Most states use a $100,000 threshold. When your sales to customers in a state exceed that threshold, you have economic nexus and must register and collect tax there.

State	Economic Nexus Threshold (2026)	Measurement Period
California	$500,000 in sales	Trailing 12 months
Texas	$500,000 in sales	Trailing 12 months
Florida	$100,000 in sales	Calendar year
Illinois	$100,000 in sales or 200 transactions	Trailing 12 months
New York	$500,000 in sales or 100 transactions	Trailing 12 months

Thresholds change. Always verify current requirements with each state's department of revenue. The timeframe to register once a threshold is crossed also varies by state — some require action within 30 days, others differ. Know your state-specific rules before you cross a threshold, not after.

Real growth scenario

Year one: $80K to California customers. $65K to Texas. $45K to Florida. No economic nexus yet. Year two: $130K to California (nexus created). $520K to Texas (nexus created). $110K to Florida (nexus created). You must now register in three additional states — on top of your store states. Economic nexus can sneak up on you.

Managing Exemption Certificates Goes Digital

In-store certificates are paper forms in a filing cabinet. Online certificates require digital submission and validation. Different workflow, same legal requirements — and the same audit exposure when something goes wrong.

❌ The manual online process

Customer orders online and gets charged tax
Customer emails a certificate after the fact
You manually refund the tax — every time, every new customer
Expired certificates go unnoticed until an audit
No renewal tracking; certificates lapse silently

✅ The automated approach

Customer uploads certificate to a portal before first order
System validates automatically — correct state, required fields, not expired
Tax exemption applies to current and all future orders instantly
Renewal reminders go out 30–60 days before expiration
No manual refunds. No expired certificates slipping through.

Learn more about automated exemption certificate storage and validation.

Manual certificate collection doesn't scale with online sales volume. As your B2B customer base grows across states, you need systems that validate at submission, track renewals automatically, and produce audit documentation instantly. ACTSOLV's CertSOLV was built for exactly this.

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Common Mistakes Retailers Make When Going Online

Mistake 1: Waiting to register until sales are "significant"

Thinking you'll worry about California when you hit $200K there. You must register once you cross the threshold — not once you feel ready.

Consequence: Back-taxes, penalties, and interest on all sales after the threshold was crossed.

Mistake 2: Using origin-based tax for all online orders

Charging your store state's rate for all online orders. Most states require destination-based sourcing — tax is based on the customer's shipping address.

Consequence: Collecting the wrong amount. Too much in some states, too little in others.

Mistake 3: Treating online certificates like in-store ones

Accepting a certificate emailed after an order and filing it without validation. The certificate must be validated before the first exempt order ships.

Consequence: Invalid certificates creating audit liability on every unvalidated transaction.

Mistake 4: Not tracking economic nexus by state

Assuming no nexus in states where you have no stores. You need monthly tracking of sales by state against thresholds — not an annual review.

Consequence: Discovering nexus obligations years late; back-taxes owed on the gap period.

Mistake 5: Forgetting marketplace facilitator rules

Collecting tax on Amazon sales when Amazon already handles it for you. Sales through facilitators (Amazon, eBay, Walmart Marketplace) are handled by those platforms.

Consequence: Double-charging customers for tax on marketplace orders.

Mistake 6: Mixing store and online exemption certificates

Using an in-store California certificate for an online Texas order. Certificates must match the customer's ship-to state — not the customer's headquarters or your store location.

Consequence: Invalid exemptions and audit assessments on all mismatched transactions.

Setting Up Tax Collection the Right Way

📋 30 days before launch

Identify all states where you currently have nexus (stores, warehouses, employees)
Verify you're registered for sales tax in all those states
Research economic nexus thresholds in your target markets

⚙️ Two weeks before launch

Configure ecommerce platform tax settings with destination-based sourcing
Enable state-specific rules for shipping and handling charges
Set up exemption certificate upload portal if you sell B2B
Test checkout with addresses from multiple states

📊 Ongoing after launch

Track sales by state monthly
Check for approaching economic nexus thresholds
Review exemption certificates for upcoming expirations
Register in new states as thresholds are crossed

What Happens If You Get It Wrong

Uncollected tax scenario

You didn't know about economic nexus in a state. You made $200,000 in sales over three years. The state audits you. You owe back-taxes on all those sales — $10,000 to $30,000 depending on the rate — plus penalties of 10% to 25%, plus interest at 6% to 12% annually.

Invalid certificate scenario

A customer's certificate expired two years ago. They made $500,000 in purchases tax-free. You owe approximately $40,000 in tax. You cannot collect it from the customer retroactively. You absorb the full liability.

If you discover past obligations: Don't just register and hope they don't notice. Consider a Voluntary Disclosure Agreement. These often limit the lookback period to three or four years instead of unlimited, and they waive penalties — though interest still applies. Acting proactively almost always produces better outcomes than waiting for an audit notice.

Frequently Asked Questions

Do I need to charge sales tax on online orders to customers in my store states?

Yes. If you have physical stores in a state, you have nexus there. You must collect sales tax on all sales to customers in that state, whether they buy in-store or online.

How do I know if I've created economic nexus in a new state?

Track your sales by state monthly. Most states use a $100,000 threshold, though some use $500,000. When you exceed a state's threshold, you've created economic nexus. Always check the state's specific timing requirement for registration — requirements vary.

Can I use the same exemption certificates for online sales that I use in my stores?

Yes, but the certificate must be valid for the state where you're shipping the product. A California resale certificate doesn't exempt a shipment to Texas. The certificate must match the ship-to state.

What if a customer sends me an exemption certificate after I've already charged them tax?

You'll need to manually refund the tax. This is why automated systems that validate certificates before checkout are valuable — they prevent this time-consuming process from happening with every new business customer.

Do marketplace facilitator rules mean I don't have to collect tax on Amazon sales?

Correct. When you sell through Amazon, eBay, Walmart Marketplace, or other facilitators, they collect and remit tax. You do not collect tax separately on those sales. However, sales through your own website require you to collect tax based on your nexus obligations.

Is shipping always taxable on online orders?

It depends on the state. In most states, shipping is taxable if the product being shipped is taxable and the shipping charge is separately stated. Rules vary significantly by state and must be configured correctly in your ecommerce platform — a blanket yes or no setting is not sufficient.

Build Compliant Online Sales Tax from Day One

Talk to a retail sales tax expert about automated solutions that handle nexus monitoring, certificate validation, and audit documentation as your online channel grows.