How to split a grocery receipt when one item is just yours

You shop together, you pay at the till, and one item in the cart is only for one of you. A bottle of hair dye, razor blades, a protein powder. Splitting the receipt in half charges the other person for something they will never use. Take the personal item off first, move its tax with it, and then split the rest.

Take the personal line off first

The personal item leaves the pile before anything is divided. Whatever stays is shared, and you split it the way you and the other person agreed: half and half, 60/40, or something else.

If you divide first and adjust afterwards, you end up undoing your own arithmetic. If you take the item off first, the rest of the receipt is an ordinary shared purchase.

The tax goes with the line

A receipt prints its tax once, as a single figure near the bottom. That figure covers every line, including the personal one. If you take $14.99 off the pile and leave the tax on it behind, the other person ends up paying half the tax on an item they did not buy.

EvenHearth spreads the receipt's tax over its lines in proportion to their prices, so each line carries the tax it attracted. A line that is one person's takes its own tax with it. What remains in the shared pile is the shared lines and the shared lines' tax.

A worked example

Sam pays for a grocery run. The receipt has six lines and $5.00 of tax, for $63.69 in all. The hair dye is Priya's. Everything else is shared, and Sam and Priya split shared costs half and half.

The hair dye comes off the top at $16.27, which is its price plus its $1.28 of tax. The five shared lines add up to $47.42. Half of that is $23.71 each.

So Sam's share of the receipt is $23.71. Priya's share is $16.27 plus $23.71, which is $39.98. The two shares add up to the receipt: $23.71 plus $39.98 is $63.69.

Split the whole receipt in half instead and each of you owes about $31.85. That leaves Priya about $8 short of what she owes.

When the shared total does not divide evenly

Suppose the shared lines had come to $47.43. Half of that is $23.715, and nobody can pay half a cent. EvenHearth works in whole cents and assigns the spare cent by a fixed rule, so the same receipt always produces the same answer and the two shares always add up to the total.

A line can also be shared on a different arrangement from the rest. If a case of sparkling water splits between you 70/30 because one of you drinks most of it, that line carries its own percentages while the others follow the household split.

Doing it in EvenHearth

Photograph the receipt with the phone app, or type the total in. On a computer, drop a photo of it into Add. The app reads the store, the date, the lines, the tax and the total into an entry. That entry is a draft until you have looked it over, which we wrote about on the Maliko Labs blog.

On the review screen every line starts as shared. Change the owner of the hair dye to Priya and it comes out of the shared pile along with its tax. If the lines do not add up to the printed total, the screen shows how far over or short they are, so you can fix a line before the entry counts.

When the entry looks right, post it. At the end of the month, closing the month shows who owes whom. You pay each other outside the app, and the app records that payment once both people confirm it. EvenHearth never moves money itself.

More on this

The receipt splitting page shows the same flow with screenshots. If you want the whole month rather than one receipt, how it works follows a shared month from the first receipt to the last transfer.