The Complete Guide to Sales Tax Filing for Online Sellers

Collecting sales tax is only half the battle—you also need to file returns and remit what you've collected. For online sellers, especially those selling in multiple states, filing can be complex. This guide walks you through the process.

Tax Filing

Understanding Sales Tax Filing

What Is a Sales Tax Return?

A sales tax return reports to the state:

• Your total sales
• Your taxable sales
• Your exempt sales
• Tax you collected
• Tax you owe

When You Need to File

You must file if:

• You're registered for sales tax in a state
• You have nexus and should be registered
• Even if you had $0 sales (in many states)

Filing Frequency

How States Assign Frequency

States assign filing schedules based on your expected tax liability:

Common Due Dates

Always check your specific state—dates vary!

Changing Frequency

As your sales grow (or shrink), states may change your filing frequency. Watch for notices.

The Filing Process

Step 1: Gather Your Data

You'll need:

Step 2: Prepare Your Return

Most state returns ask for:

• Gross sales in the state
• Exempt sales (resales, exempt products)
• Taxable sales
• Tax collected
• Tax due (calculated)

Step 3: Calculate What You Owe

Tax Due = Tax Collected + Adjustments - Credits

Adjustments might include:

• Corrections from previous periods
• Bad debt deductions
• Discounts for timely filing

Step 4: File the Return

Most states offer:

• Online filing (most common)
• Paper forms (slower, sometimes unavailable)
• Third-party software integration

Step 5: Pay the Tax

Payment options:

• ACH bank transfer (usually free)
• Credit card (often has fees)
• Check (slower)

State-by-State Filing

Filing in Multiple States

If you have nexus in multiple states, you'll file separately in each:

Streamlined Sales Tax (SST)

If you're registered through SST, you may be able to:

• File multiple states in one portal
• Use certified service providers
• Simplify multi-state compliance

What Online Sellers Report

Marketplace Sales

For sales on marketplaces (Amazon, eBay, etc.):

Check each state's specific requirements.

Your Own Website Sales

Sales through your own store:

• You collected the tax
• You report and remit

Combined Reporting

Your return often combines:

• Marketplace sales (for reference)
• Direct sales (you collected)
• Total tax responsibility

Common Filing Scenarios

Scenario 1: Single State, Own Website

Situation: You sell only in California through your Shopify store.

Filing:

• California monthly/quarterly/annually
• Report all CA sales
• Remit tax you collected

Scenario 2: Multi-State, Mostly Marketplaces

Situation: You sell on Amazon nationwide but have your own website too.

Filing:

• Home state: Report all sales, show marketplace portion
• Other nexus states: May be $0 returns (marketplace collected)
• Track for records regardless

Scenario 3: Multiple Channels, Multiple States

Situation: You sell on Amazon, eBay, your website, and at a local store.

Filing:

• Multiple state registrations
• Complex tracking needed
• Consider automation

Sales Tax Automation

When to Automate

Consider automation if you:

• File in more than 2-3 states
• Spend hours tracking sales tax
• Have made filing errors
• Want to reduce stress

What Automation Does

Popular Services

Record Keeping for Filing

What Records to Keep

Organizing Your Records

Create a system:

• Folder per state
• Subfolders by year
• Digital copies of all filed returns
• Payment confirmation receipts

Multi-Platform Tracking

Selling across multiple platforms? Use tools like Raidframe to:

• Track sales across channels
• Generate reports by state
• Calculate tax collected per platform
• Prepare for filing

Common Filing Mistakes

Mistake 1: Missing Deadlines

Late filing = penalties + interest.

Solution: Calendar all due dates, set reminders 5-7 days before.

Mistake 2: Forgetting $0 Returns

Many states require filing even with no sales.

Solution: File every period, even if $0.

Mistake 3: Wrong Reporting of Marketplace Sales

Incorrectly reporting marketplace facilitator sales.

Solution: Check each state's specific rules.

Mistake 4: Calculation Errors

Simple math errors can trigger notices.

Solution: Double-check or automate.

Mistake 5: Not Keeping Records

When audited, can you prove your filings?

Solution: Keep everything organized and accessible.

Penalties for Late or Non-Filing

Types of Penalties

Getting Help

If you're behind:

• File as soon as possible
• Contact the state about payment plans
• Consider voluntary disclosure programs
• Consult a tax professional

Filing Calendar Example

For a seller filing monthly in one state, quarterly in two others:

Simplifying Your Filing

Option 1: Single Channel, Single State

Keep it simple:

• Track sales in one place
• File one return
• Manageable manually

Option 2: Use Platform Reports

Platforms provide sales reports:

• Amazon tax reports
• eBay sales downloads
• Shopify tax reports

Option 3: Automate Everything

For complex situations:

• Invest in tax software
• Integrate with sales channels
• Automatic calculation and filing

Getting Started

Proper filing starts with proper registration. Make sure you have your sales tax permit and resale certificate.

Apply for Your Resale Certificate →

Need help with sales tax compliance? Contact us for guidance.