Sales tax

In the United States, the price tag and the checkout total can differ because sales tax may be added when you pay. The taxable purchase amount, sometimes called the tax base, is the amount subject to tax, which need not equal the whole receipt subtotal. At a hypothetical 8% rate, a $150 purchase that is entirely taxable costs $162 when there are no other charges.

In a sentence

• "With an assumed 8% sales tax on the full price, my $150 purchase costs $162."
• "Income tax is based on taxable income, while sales tax is based on taxable purchases."
• "I split the receipt's sales tax between the items it applies to."

How it's calculated

For a purchase with one applicable rate and no additional charges, the calculation is:

Sales tax = taxable purchase amount × sales tax rate

Total paid = purchase subtotal before tax + sales tax

1. Identify the taxable purchase amount. Check which items are subject to tax under the rules for that transaction rather than assuming a mixed receipt is entirely taxable.
2. Identify the applicable rate. State and local rates may combine, and different types of purchases can have different tax treatment.
3. Convert the percentage to a decimal and multiply. For the hypothetical 8% rate, multiply the taxable amount by 0.08.
4. Check the final receipt. Use the actual tax charged and total paid for your records; if the displayed price already includes tax, do not add it again.

If different rates apply to different items, calculate the tax for each taxable portion separately rather than applying one rate to the entire subtotal. An exempt item still contributes to the purchase total even though no sales tax is charged on that item.

An example

Suppose you buy $50 of household supplies and $100 of clothing. Assume both are fully taxable at the same hypothetical 8% combined rate, with no discounts or other charges.

The tax is $150 × 0.08 = $12, and the checkout total is $150 + $12 = $162. If you split the purchase between two budget categories, recording $54 for household supplies and $108 for clothing keeps the category amounts equal to the full charge.

Why it matters

Sales tax changes how much cash a purchase requires. A spending limit based only on shelf prices can be exceeded at checkout even when you buy exactly what you planned. Assigning each item's associated tax to its budget category lets you compare the full cost of that spending with the amount you allowed.

Sales tax also helps explain why an asset's purchase cost and current value differ. Paying tax on a car does not guarantee an equal increase in what someone else would pay for the car. Depreciation is a separate decline in the asset's value over time, not another name for the tax paid when buying it.

Sales tax versus income tax and merchant fees

Sales tax applies to taxable purchases, income tax applies to taxable income, and a merchant fee is a business's charge rather than a tax. Income tax withheld from your paycheck does not prepay the sales tax on what you later buy.

A merchant's delivery charge or service fee is not sales tax merely because it appears after the subtotal. Whether that fee is itself subject to sales tax depends on the applicable rules. Read the receipt lines separately rather than treating every amount beyond the merchandise price as tax.

Common questions

Is the sales tax rate the same everywhere? No. State and local rates and taxable-purchase rules vary, so the 8% rate in the example is an assumption, not a rate to use for your own purchases.

Is sales tax charged on everything? No. Whether a good or service is taxable depends on the applicable rules and any exemption. Do not assume that clothing, groceries, services, or other purchases receive the same treatment in every jurisdiction.

Is sales tax included in the sticker price? Not necessarily. Check whether the stated price includes tax and compare it with the checkout total. Adding tax to a price that already includes it overstates what you need to pay.

Do I need a separate budget category for sales tax? No. You can include sales tax in the category of the purchase it belongs to, or track it separately if that serves your reporting needs. Either way, count the tax once and make sure the recorded parts add up to the full charge.

Go deeper

• How to split one purchase across categories explains how to allocate receipt items and their tax while keeping the parts equal to the original charge.
• Why your net worth drops when you buy a car separates the cash and borrowing used for a purchase from the vehicle's recorded value.
• The Budget calculator splits monthly take-home pay into needs, wants, and savings using the 50/30/20 rule or shares you choose.