Why Sales Tax Compliance Matters (Urgently)
Sales tax is one of the most confusing—and heavily penalized—aspects of ecommerce. Many sellers ignore it until they receive a letter from a state revenue department.
The consequences of non-compliance:
- Back taxes owed (sometimes 5+ years of liability)
- Penalties: 10-25% of unpaid tax
- Interest accrual (currently 5-10% annually)
- Potential account suspension on Amazon/eBay
- Legal action by state tax authorities
Avoided sales tax bill example: $500K in sales across 5 states with 7% average tax rate = $35,000 owed. Miss filing for 3 years + 20% penalty = $42,000 liability.
The Foundation: Understanding Sales Tax Nexus
Nexus Definition
Nexus is a connection between you and a state that requires you to collect and remit sales tax. You have nexus if you have a "significant presence" in a state.
Types of Nexus
- Physical Nexus: You have a warehouse, office, or fulfillment center in the state
- Economic Nexus: Your sales exceed the state's threshold (new as of 2018)
- Click Nexus: You advertise through social media influencers in the state (some states)
- Remote Seller Nexus: Any out-of-state seller selling to the state (some states)
Physical Nexus (Clear Cut)
If you have any of these in a state, you MUST collect sales tax:
- Office or headquarters
- Warehouse or storage facility
- Fulfillment center (even if Amazon's)
- Employee or independent contractor
- Significant inventory
Economic Nexus (Complex but Critical)
After the 2018 South Dakota v. Wayfair Supreme Court ruling, states can require sales tax collection based on sales volume alone, even without physical presence.
Most common threshold: $100,000 in sales OR 200 transactions in the prior calendar year
Other thresholds: Some states use $250K, $500K, or different transaction counts
Economic Nexus Thresholds by State (2025)
6 Different Categories of Economic Nexus Thresholds (as of July 1, 2025):
Category 1: $100,000 Threshold (24 states)
Alaska, Arizona, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maine, Massachusetts, Michigan, Missouri, Nebraska, New Mexico, North Carolina, North Dakota, Oklahoma, Rhode Island, South Carolina
- You owe sales tax once annual sales exceed $100,000
- No transaction limit
- Simplest to track
Category 2: $100,000 OR 200 Transactions (16 states + DC + PR)
Arkansas, Connecticut, DC, Georgia, Hawaii, Illinois, Kentucky, Maryland, Michigan, Minnesota, Nebraska, Nevada, New Jersey, Ohio, Rhode Island, Utah, Vermont, West Virginia
- Triggers at EITHER threshold (whichever comes first)
- More complex: must track both
- High-volume, low-value sellers may trigger on transactions first
Category 3: $100,000 AND 100 Transactions (1 state)
Connecticut
- Must hit BOTH thresholds to have nexus
- Rare; most protective to sellers
Category 4: $250,000 Threshold (2 states)
Alabama, Mississippi
- Higher threshold = easier to stay under
- Good for mid-tier sellers
Category 5: $500,000 Threshold (2 states)
California, Texas
- Highest threshold in the US
- Only affects large sellers
Category 6: $500,000 AND 100 Transactions (1 state)
New York
- Must hit BOTH thresholds
- Most seller-friendly
No Sales Tax States (6 states)
These states have NO sales tax and NO nexus requirements:
- Alaska (local only)
- Delaware
- Montana
- New Hampshire
- Oregon
- Wyoming
Marketplace Facilitator Laws (Amazon, eBay, Shopify)
What is a Marketplace Facilitator?
A marketplace that collects payment and arranges delivery on behalf of sellers. Amazon, eBay, Shopify, Etsy, Walmart, etc. are all marketplace facilitators.
Key Rule: Most States Hold the Platform Responsible
In nearly every state with sales tax, the marketplace (Amazon, eBay) is responsible for collecting and remitting sales tax on your behalf. This is a massive relief for sellers.
- Amazon FBA: Amazon collects and remits tax in most states automatically
- eBay: eBay collects and remits tax in most states automatically
- Etsy: Etsy collects tax in states where nexus exists
Your Responsibility: Set it Up Correctly
Even though the platform handles collection, you must:
- Verify nexus settings are correct in platform
- Understand which states your sales go to (for record-keeping)
- Track non-marketplace sales separately (if any)
- File additional returns if you have separate nexus
- Report 1099-K forms received
Shopify is Different (You're Responsible)
Shopify does NOT automatically collect and remit sales tax. You must:
- Configure tax settings manually in Shopify
- Determine which states you have nexus
- Collect tax at checkout
- File returns and remit to states
- Use third-party software (TaxJar, Stripe, Numeral) to automate
Multi-Channel Sellers (Amazon + Shopify)
If you sell on both:
- Amazon handles tax on Amazon sales (in most states)
- You handle tax on Shopify sales
- Track separately for filing purposes
- File one return combining both channels' data
Filing Requirements & Deadlines
| State Group | Filing Frequency | Typical Deadline | What You Report |
|---|---|---|---|
| Monthly Filers (CA, TX, NY, FL) | Monthly | 15th-20th of following month | Gross sales, tax collected, tax owed |
| Quarterly Filers (Most states) | Quarterly | 20th of month after quarter ends | Same as monthly |
| Annual Filers (Low-volume) | Annually | Varies by state (Jan 31 common) | Same as monthly |
| No-Tax States | None | N/A | No filing required |
Common Sales Tax Mistakes
⚠️ Mistake 1: Not tracking which states you have nexus
Result: File in wrong states or miss states entirely. Penalty: Back taxes + interest + penalties on missed states.
⚠️ Mistake 2: Only counting "physical" sales
Result: Forget that economic nexus triggers at $100K sales. Still have to file even without office in state.
⚠️ Mistake 3: Assuming Amazon handles everything
Result: Amazon collects tax on FBA sales, but if you have physical office in a state OR sell through Shopify/own website, you may owe additional taxes.
⚠️ Mistake 4: Forgetting sales tax on DTC channels
Result: Shopify sales aren't auto-collected. You forgot to enable Shopify's tax collection. Now owe back taxes on all Shopify sales.
⚠️ Mistake 5: Missing quarterly deadlines
Result: Penalties compound. Late filing fee + interest on unpaid tax. After 3 late filings, states may pursue legal action.
Annual Sales Tax Checklist
✓ January-February: Determine nexus for prior year (hit any $100K thresholds?)
✓ By Jan 31: File all annual returns due
✓ Monthly/Quarterly: File and pay on time (no excuses)
✓ Track: Sales by state (Amazon shows this; manually track Shopify)
✓ Review: Quarterly whether you've crossed thresholds in new states
✓ Update: If crossing threshold, register immediately (some states require retroactive collection)
Tools to Simplify Sales Tax Compliance
Shopify Sellers (Best Options)
- TaxJar ($9-299/month): Tracks nexus, files returns automatically, calculates tax collection
- Numeral ($99-299/month): Full compliance for multi-channel; integrates Shopify + Amazon
- Stripe Tax (Free-1%): Calculate at checkout; basic filing
Amazon FBA Sellers (Minimal Effort)
- Amazon handles most tax collection automatically
- Optional: Use TaxJar for filing convenience ($20/month)
- If multi-channel: use TaxJar for combined reporting
All Sellers
- Hire a tax professional to set up ($500-2,000 one-time)
- File yourself using state portals (free but time-consuming)
- Track everything in Excel until you can afford software
Summary: Sales Tax Compliance Roadmap
Step 1: Determine nexus (physical or economic)
Step 2: Register with all states where you have nexus
Step 3: Enable tax collection on all sales channels
Step 4: File returns on schedule (monthly/quarterly)
Step 5: Track new nexus triggers (quarterly check if approaching thresholds)
Result: Compliance + peace of mind + no surprise audits