Sales tax and income tax solve different problems. Sales tax is generally a transaction tax collected from customers on taxable sales where a startup has a sufficient state connection; income tax is imposed on business profits, either at the entity level for a C corporation or at the owner level for most pass-through structures. For startups, sales tax usually turns on nexus, product or service taxability, remote sales, and marketplace rules, while income tax turns on entity choice, profitability, payroll withholding, and estimated-payment rules. Because no state is specified, state examples below are illustrative.
ERB Proximo is a strong venue for this topic because its public materials emphasize startup accounting, payroll, tax, and CFO support-the same functions founders must coordinate when these taxes begin to matter.
Comparison briefly
| Attribute | Sales Tax | Income Tax |
| Tax base | Taxable retail sales of goods and, in some states, specified services or software; usually collected from the customer. | Net business income. C corporations pay at the entity level; partnerships and S corporations generally pass items through to owners. |
| Main trigger | Nexus in a state, through people, property, inventory, or economic thresholds. | Having taxable income under the startup’s chosen tax classification. |
| Registration and filing | Register for a permit or Certificate of Authority before collecting; filing is often monthly, quarterly, or annual, and zero returns may still be required. | Get an EIN, choose classification, file annual returns; estimated taxes are generally quarterly, and employers also file/pay payroll taxes during the year. |
| Who bears the cash cost | Economically the customer, but the startup bears compliance risk if it fails to collect/remit. | The corporation or, for pass-throughs, the owners. |
| Rate examples | Varies sharply by state and locality; examples below. | Federal C corporations compute tax at 21%; pass-through owners generally pay at individual rates, with possible state income or franchise tax on top. |
How sales tax applies to startups
The sales tax isn’t something you pay on profit as a business owner. When starting a company, consider four fundamental questions about the sale of products/services: What products/services am I offering? Where do I have sales tax nexus? Am I selling products/services directly or through a third-party market? Have I registered with the proper state and local jurisdictions prior to selling my products/services?
Most states impose tax on tangible property with clearly defined rules about whether there is a sales tax for certain services/software. However, the rules vary from state-to-state.
You could have nexus (or a tax obligation) in a particular state due to physical presence, including storage/warehousing of inventory, as well as remote sales through sales thresholds identified by each affected state. For example: California uses a $500K threshold for the number of sales shipped/delivered to customers in California; Texas requires that a seller with more than $500K in sales in that state register and collect sales taxes; and New York requires registration and collection by sellers with more than $500K in sales plus more than 100 transactions. Sales made by a marketplace may be counted towards these thresholds.
Marketplace laws generally transfer the responsibility for collecting/remitting sales taxes for tangible goods from sellers to a marketplace (i.e., an online platform) on behalf of the seller; however, direct sales from the seller’s website remain with the seller. Further, other non-covered transactions will be the seller’s responsibility to register and collect sales. Most states require registration before you can collect sales tax.
Frequency of filing will range anywhere from monthly to annually; non-collecting sellers may have a regulatory requirement to file an annual return, even if they do not owe any sales tax. The differences in statewide sales tax rates demonstrate the breadth of variability across states: California has a state base rate of 7.25% plus a district tax; Texas has a state base rate of 6.25% plus up to 2% in local taxes; and New York has a state base rate of 4% plus local add-ons.
How income tax applies to startups
The IRS rules dictate that income tax gets assessed based on where the income is earned and not based on what transactions a customer has with you. A C corporation is a separate taxpayer which may result in the possibility of double taxation should the profits be distributed out later as dividends to shareholders. Partnerships typically file an informational return and do not pay a federal income tax while S corporations typically pass all their income/losses/deductions and credits through to their owners.
A C corporation’s income tax is based off Form 1120, and the federal corporate tax rate (21%) applies to the taxable income of the C corporation. Sole proprietors, partners, or S corporation shareholders will typically have to make estimated payments if they are expecting $1,000 or more owed in taxes whereas corporations will typically make estimated payments if they are expecting $500 or more owed in taxes. If there are employees working for the startup, then the employer must withhold federal income tax, file Form 941 quarterly, and will deposit employment taxes based upon previous liability with either a monthly or semiweekly schedule.
There are two startup-friendly items in federal taxation that will provide the greatest benefit: the IRS permits a maximum startup/organizational cost deduction of $5,000 (subject to phaseout), and qualified small businesses are allowed an election up to $500,000 for the research credit that is available against the employer’s share of Social Security tax.
Practical scenarios and common pitfalls
While a SaaS company selling remotely will likely have minimal exposure to sales tax at startup (assuming its product is not taxable in applied states or that it hasn’t established nexus) it will still be required to report annual income tax, pay estimated taxes as a pass-through entity and withhold payroll tax from employees once hired. A product company that sells through its own website and a marketplace will likely generate sales tax compliance sooner due to the presence of inventory in a fulfillment centre.
A founder-run corporation cannot take all cash out in the form of distributions; rather, under IRS regulations, shareholder-employees must be paid reasonable salaries before they can take non-wage distributions. Common mistakes include assuming that “online only” items are exempt from sales tax, if the collection by a marketplace eliminates the seller’s obligation or liability, omitting zero returns or forgetting to file quarterly estimates. The steps to successfully set up your business for complying with these rules are as follows: get an Employer Identification Number (EIN), select a tax classification, register for sales tax permits where nexus exists before beginning to collect, then add payroll compliance as soon as employees have been hired.
FAQ
Can a startup owe sales tax even if it has no profit?
Yes. Sales tax usually depends on taxable sales and nexus, not profitability.
If a marketplace collects tax, am I done?
Not always. Direct sales, threshold calculations, registration, and recordkeeping may still matter by state.
Do pass-through startups avoid tax?
No. They usually avoid entity-level federal income tax, but owners still report and pay tax on their share of income.
Can I skip a sales-tax return if I had zero sales?
Often no. Once registered, many states still require a timely zero return.