How to Calculate Sales Tax

In the United States, sales tax is calculated as a percentage of the retail price of certain goods or services. The tax is legislated and regulated at the state level and provides revenue for government operations. 

Sales tax is a consumption tax paid by consumers at the point of sale. Businesses are then responsible for remitting it to the government.

How State Tax Is Determined

Sales taxes are administered at the state level, but they can be levied at the municipal or county level as well. Alaska, for example, has no state sales tax, but many municipalities within Alaska levy sales taxes that range from 1% to 7%.

Not all states have a sales tax. Besides Alaska, Delaware, Montana, New Hampshire, and Oregon do not levy any state sales taxes. The sales tax rate in the United States ranges from 0% in the aforementioned states to 7.25% in California, with Indiana, Mississippi, Rhode Island, and Tennessee following closely at 7%.

Sales tax does not apply to all goods and services; most states have exemptions on certain categories, such as food, clothing, medicine, newspapers, and utilities. The exemption categories vary by state.

Another consideration is that sales tax may be charged for online sales, depending on whether the seller is considered to have nexus in a state. Generally, for tax purposes, nexus is understood to mean a physical presence, such as a warehouse, office, or employee who resides in the state.

However, this definition comes into tension with the presence of mass ecommerce retailers, such as Amazon. In an attempt to capture tax on online sales, several states have passed “Amazon laws,” which have shifted the definition of nexus.

What that means is that although online sellers such as Amazon may not have a physical presence in a given state, they may be recognized as having a “constitutionally significant connection” to that state and are therefore required to pay sales tax in certain states.

Sales Tax Calculation and Formula

Calculating sales tax is simple as long as you understand state sales tax rates and collection requirements in the state(s) where the transactions are taking place. It’s important for businesses to ensure that they have complete information on applicable tax rates to remit the correct amount of tax to the government. 

Here’s how to calculate the sales tax on an item or service:

• Know the retail price and the sales tax percentage.
• Divide the sales tax percentage by 100 to get a decimal.
• Multiply the retail price by the decimal to calculate the sales tax amount.

Expressed as a formula, the calculation is:

(Sales tax percentage ÷ 100) × price of good or service

The final price of the item is the amount of tax plus the original price of the item before tax.

Examples of Sales Tax Calculations

Let’s say Joe W. is buying a chair for $75 in Wisconsin, where the tax rate is 5%. Here’s how the tax would be calculated:

• 5 ÷ 100 = 0.05 
• 0.05 × $75 = $3.75

The amount of sales tax that would apply to Joe’s purchase of this chair is $3.75. Once the tax is added to the original price of the chair, the final price including tax would be $78.75. 

Here’s another example: Janis B. is purchasing a laptop for $1,200 in California, where the sales tax rate is 7.25%. Here’s what that calculation would look like:

• 7.25 ÷ 100 = 0.0725
• 0.0725 × $1,200 = $87

Eighty-seven dollars in sales tax would need to be added to the original price of the laptop. The final price of the laptop would be $1,287.

The Bottom Line

Sales tax is a simple calculation based on the percentage of a retail price of a good or service. To calculate it, convert the sales tax percentage to a decimal, then multiply it by the retail price of the product or service.

It is important to understand the tax rate as well as the collection requirements for the area in which the transaction is being made, so that consumers understand the final price of the item, and so that businesses can anticipate how much tax they are responsible for remitting to the government.