Sales tax is one of the most confusing areas for freelancers and small business owners who are just getting started with invoicing. Unlike income tax, which applies to everyone, sales tax requirements vary dramatically based on what you sell, where you sell it, and where your customer is located. Getting it wrong can result in unexpected liabilities, penalties, and the unpleasant experience of owing tax you never collected. This guide will help you understand when sales tax applies to your invoices and how to handle it correctly.
Do You Need to Charge Sales Tax?
The answer depends on three factors: whether you have nexus in a state, whether your product or service is taxable in that state, and the applicable rate. Let's break each one down.
What Is Nexus?
Nexus is the legal connection between your business and a state that creates a sales tax obligation. You have nexus in a state if you have a physical presence there (an office, warehouse, employee, or inventory) or if you exceed that state's economic nexus threshold (typically $100,000 in annual sales). Some states also apply a transaction count test, but many have removed it — check your specific state's rules. Since the Supreme Court's Wayfair decision in 2018, most states have adopted economic nexus rules, meaning even remote sellers can have sales tax obligations in states where they have no physical presence.
Services vs. Products: What Is Taxable?
Most physical products (tangible personal property) are taxable in states that have sales tax. Services are more complicated. Each state decides independently which services are subject to sales tax, and the rules vary widely.
- Most states do not tax professional services like consulting, legal advice, or accounting
- Some states tax digital products and SaaS (Software as a Service)
- Design, marketing, and creative services are taxable in certain states
- Repair and maintenance services are often taxable
- Educational and training services have mixed treatment across states
- Five states have no sales tax at all: Alaska, Delaware, Montana, New Hampshire, and Oregon
How to Determine Your Sales Tax Rate
Sales tax rates are not uniform. The rate on your invoice may include multiple components: a state rate, a county rate, a city rate, and sometimes special district rates. The combined rate can vary block by block in some metropolitan areas.
Origin-Based vs. Destination-Based States
Some states use origin-based sourcing, where you charge the sales tax rate of your business location. Others use destination-based sourcing, where you charge the rate of the buyer's location. Most states use destination-based sourcing for remote (out-of-state) sellers. Knowing which model your state follows is critical for calculating the correct rate.
Adding Sales Tax to Your Invoices
When you determine that sales tax applies, your invoice should clearly display it as a separate line item. Never bury tax inside your service fees or product prices without disclosure. A properly formatted invoice with sales tax includes specific elements.
- Subtotal of taxable goods or services
- Subtotal of non-taxable items (if applicable)
- Sales tax rate applied
- Sales tax amount calculated
- Grand total including tax
- Your sales tax permit or registration number
InvoiceFold allows you to configure tax rates per client or per jurisdiction, automatically calculating the correct amount on each invoice. This eliminates manual calculation errors and ensures every invoice meets compliance requirements.
Registering for a Sales Tax Permit
Before collecting sales tax, you must register for a sales tax permit in each state where you have nexus. Collecting sales tax without a permit is illegal in most states. Registration is typically done through the state's department of revenue website and is usually free. Once registered, you will receive a permit number that should appear on your invoices and be renewed according to the state's schedule.
Filing and Remitting Sales Tax
Collecting sales tax is only half the obligation. You must also file sales tax returns and remit the collected tax to the state on a regular schedule, which can be monthly, quarterly, or annually depending on your volume. Late filings result in penalties and interest. Some states offer discounts for timely filing.
- Determine your filing frequency based on state requirements and your sales volume
- Track all taxable sales and tax collected throughout each period
- File your sales tax return by the due date
- Remit the collected tax to the state
- Keep records of all returns and payments for at least four years
Exemptions and Resale Certificates
Some customers may be exempt from sales tax, such as non-profit organizations, government agencies, or businesses purchasing items for resale. In these cases, the customer should provide you with a valid exemption or resale certificate. Keep these certificates on file; if audited, you will need to produce them to justify why tax was not collected on those transactions.
Common Sales Tax Mistakes
- Collecting sales tax without a permit
- Using the wrong rate (especially in destination-based states)
- Failing to collect tax in states where you have economic nexus
- Not filing returns in periods with zero taxable sales (many states require zero returns)
- Absorbing the tax instead of charging it to customers
- Forgetting to update rates when jurisdictions change them
Simplifying Sales Tax Compliance
Sales tax compliance can feel overwhelming, especially if you sell across multiple states. The key is to start with the states where you clearly have nexus, register for permits, configure your invoicing tool with the correct rates, and file returns on schedule. InvoiceFold supports multi-jurisdiction tax configuration, making it straightforward to set the right rate for each client and generate tax-inclusive invoices automatically. As your business grows into new states, you can add jurisdictions without overhauling your entire invoicing process.