The Dilemma of the Group Dining Check
Imagine a group dinner with six friends. Two people order cocktails and prime steaks ($85 each), while two non-drinkers order basic pasta entrees and tap water ($22 each). When the check arrives, splitting the $360 total evenly ($60 per person) forces the lower spenders to subsidize the premium orders.
The Proportional Tax & Tip Formula
When itemizing a dining check, simply adding up base food items is incomplete—sales tax and gratuity (tip) must be allocated proportionally based on each person's subtotal share.
Worked Formula for Itemized Dining Splits
Individual Final Total = Subtotal_Individual × (Total Invoice Amount / Subtotal_Group)
This single multiplier automatically distributes sales tax, service fees, and gratuity perfectly across everyone according to what they consumed.
Handling Shared Appetizers & Desserts
For shared items like a $24 guacamole appetizer shared by four people, divide the appetizer cost ($6 each) before applying the tax/tip multiplier. FairShareUp handles this math automatically with receipt item tagging.