When you tip at a restaurant, the standard practice is to calculate the gratuity on the pre-tax subtotal rather than the total after sales tax. So no, you do not tip on tax by convention. Both approaches are socially acceptable and no server will refuse the extra dollar, but tipping on the post-tax figure means paying a gratuity on a government charge that has nothing to do with your service.
How Much the Choice Actually Costs You
The pre-tax subtotal is the price of everything you ordered before the sales tax line. Tip 20% on that number and the gratuity tracks the food and service you received. Switch to the post-tax total in a city with 8% sales tax and a $100 meal’s tip goes from $20.00 to $21.60.
On one check that’s pocket change. Across a year of regular dining out, it adds up. If rounding off the bottom line is easier and you’re comfortable with the number, no one is going to correct you. The point is that you have a choice, and many diners never realize it, especially when a tablet has already made the choice for them.
Why the Payment Terminal Often Decides for You
Handheld tablets and countertop terminals shape tipping behavior more than any etiquette guide. The suggested-tip buttons, usually 18%, 20%, and 25%, can be calculated on either the pre-tax subtotal or the post-tax total depending on how the restaurant set up its software. At least one major point-of-sale platform defaults to pre-tax, but individual owners can flip that setting and many do.
You often can’t tell which base the machine used without doing the math. On a $100 meal in an area with 8% sales tax, a suggested 20% tip of $21.60 means the system used the post-tax total of $108. A suggestion of $20.00 means it used the subtotal. If you care about the difference, use the custom-tip button and enter your own number. That’s the only reliable way to tip on the subtotal when the terminal defaults to the total.
A Quick Way to Check
Find the subtotal line, not the total. Move the decimal one place left to get 10%, then double it for 20%. If you want to leave more or less, adjust from there. This works in your head faster than reading the tablet’s fine print, and it puts you in control of the base regardless of what the screen suggests.
Automatic Gratuities Are a Different Animal
The tip you choose to leave and the fee a restaurant adds to your bill are not the same thing under federal tax rules. The IRS treats a payment as a tip only when the customer paid it freely, chose the amount, wasn’t given a rate set by the restaurant, and could generally direct who received it. When any of those conditions is missing, the payment is a service charge.1Internal Revenue Service. Rev. Rul. 2012-18
The most common example is the automatic 18% gratuity added for large parties. It’s labeled “gratuity” on the check, but because the customer didn’t set the amount and couldn’t decline, the IRS classifies it as a service charge. The restaurant reports it as regular wages on the employee’s paycheck rather than as tip income.2Internal Revenue Service. Announcement 2012-25
That distinction matters for your bill in another way. A voluntary tip is generally exempt from sales tax because it isn’t part of the purchase price. A mandatory service charge often is part of the restaurant’s gross receipts, and many states apply sales tax to it at the same rate as the food. If you see an automatic gratuity on your check, look at whether the tax line was calculated before or after it was added. The rules vary state to state, and some draw finer distinctions based on how the charge is distributed to employees, but as a general rule a mandatory charge is taxable.
One practical consequence: if an automatic gratuity is already on the check, you have already tipped. Adding another 20% on the tip line on top of that is a common accident when the check is long and the eye goes straight to the total.
What the Server Owes on the Tip You Leave
Tips are taxable income to the person who receives them. Servers are required to keep a daily record of tips, report any month’s tips totaling $20 or more to their employer by the 10th of the following month, and include all tip income on their annual return. Employers withhold federal income tax, Social Security, and Medicare from reported tips the same way they do from regular wages.3Internal Revenue Service. Tip Recordkeeping and Reporting
This means the number you write on the tip line isn’t what lands in your server’s pocket. Payroll taxes come out of it, and if you paid by credit card the restaurant may also pass along a proportional share of the card processing fee, provided the deduction doesn’t drop the employee below minimum wage.4U.S. Department of Labor. Fact Sheet 15 – Tipped Employees Under the Fair Labor Standards Act Cash tips avoid the processing fee, which is one reason some servers prefer them.
None of this changes the etiquette answer. Tip on the subtotal, tip on the total, or tip a flat amount that feels right for the service. Just know which base your terminal used before you tap the button, and read the check for an automatic gratuity before you add your own.