The fair way to split tax and tip on a group bill

What's the most common mistake splitting tax and tip?

Imagine two people: one orders $60 of food, the other orders $20. They correctly each pay for their own food. Then they split a 20% tip ($16) evenly — $8 each. The light eater just paid 40% of the tip on 25% of the food. That's backwards.

Tip and tax scale with the size of an order, so they should be divided the same way the food is.

Why is a proportional split fairer?

Tax is literally a percentage of the subtotal, and a percentage tip is too. If your food was 25% of the table's subtotal, your fair share of a percentage-based tax and tip is also 25%. Splitting them proportionally simply keeps everyone's slice consistent from the subtotal all the way to the final total.

What does a proportional tax-and-tip split look like?

Say the subtotal is $80: Person A ordered $60, Person B ordered $20. Tax is $7 and the tip is $16, for a $103 total.

Proportional split: A's share is 60/80 = 75%, so A pays 0.75 × ($7 + $16) = $17.25 on top of their $60 → $77.25. B pays 25% → $5.75 on top of $20 → $25.75. The two totals add up to $103, and each person carried tax and tip in line with what they ordered.

Tip on pre-tax or post-tax?

Either is defensible; tipping on the pre-tax subtotal is slightly more common and arguably more correct since you're tipping on the food and service, not the government's cut. The bigger fairness lever is splitting whatever tip you choose proportionally, not whether the base included tax.

What about service charges and auto-gratuity?

Large parties often get an automatic gratuity (commonly 18–20%) baked into the bill. If it's already there, don't tip again on top by accident. Split the existing service charge proportionally just like a tip, and only add more if the group decides the service warranted it.

Should you tip on the tax?

Tipping on the pre-tax subtotal is the more common convention — the tip is for the food and the service, not the sales tax. On a small check the difference is pennies; on a large group tab it might be a dollar or two. Pick one approach and apply it to everyone. The fairness that actually matters is splitting whatever tip you land on proportionally, not whether the base included tax.

How do you split the tip when one person didn't drink?

Alcohol is usually the biggest swing in a group bill, so this comes up constantly. Because a proportional split ties each person's tip to their own items, the non-drinker automatically pays tip only on their food — no special-casing required. Split the tip evenly instead and the person who skipped the $14 cocktails quietly subsidizes everyone who didn't, which is the exact unfairness proportional splitting removes.

Is a flat amount per person ever fair for tip?

A flat per-head tip (say $8 each) is fast, but it's an even split in disguise — it overcharges the small orders and undercharges the big ones, just like dividing the whole total by the number of people. It's fine among friends who ordered similarly; for a mixed table, a percentage of each person's own subtotal stays fair with no extra effort once a tool is doing the arithmetic.

Let the tool do the percentages

Tab Tender distributes tax, tip, and service charges proportionally by default, so you never have to run these percentages by hand — assign the items and the fair totals are calculated for you.