It happens most weeks for anyone running more than one job at a time: one supplier trip, a trolley with materials for two different sites, one receipt at the till. Tag the whole thing to whichever job happens to be open on the app and you've just overstated one job's cost and understated the other's — not by a huge amount most of the time, but often enough that neither job's total can actually be trusted.
Why a whole receipt on one job is worse than it looks
The error doesn't cancel itself out. Job A ends up looking like it ran over budget on materials when it didn't; Job B looks artificially cheap, which is exactly the kind of false signal that leads to under-quoting a similar job next time. Multiply that across a year of shared supplier runs and the "materials per job" number you're relying on to quote future work is quietly unreliable across the board.
The fix: allocate, don't dump
The receipt itself doesn't need to be split physically — most receipt-scanning tools let you log one scanned receipt against more than one job, entering the portion that actually applies to each. If the itemized lines are visible on the receipt, allocating by actual line item is the most accurate approach. If it's just a lump sum for a trolley of mixed materials, a reasonable estimate split by proportion of the job's needs is good enough — better an honest estimate than a total attached to the wrong job entirely.
A worked example
Say a merchant run comes to 240 total: 150 of timber for a fencing job, and 90 of fixings and sealant for a separate bathroom job running the same week. Tagging the whole 240 to whichever job happened to be open when the receipt was scanned means one job's materials total is overstated by 90 and the other's understated by the same — a genuinely misleading number for both, however accurate the receipt itself is.
When it's not worth splitting
Not every mixed purchase needs precision. A handful of screws or a tube of sealant that's genuinely incidental to a much bigger job total isn't worth the admin of splitting — tag it to whichever job it's mostly for and move on. The habit matters most for purchases large enough to actually move a job's number.
How Site Wallet handles this
A scanned receipt can be allocated across more than one job, with the portion for each entered at the time it's tagged — so a single supplier run for two sites doesn't distort either job's running total. The original receipt stays attached to both jobs for the record, with only the relevant share counted toward each one's cost.
FAQ
Do I need to keep two copies of the receipt?
No — the same scanned image can be linked to both jobs, with each job showing its own allocated share of the total, so there's no duplication needed for the record itself.
What if I get the split slightly wrong?
An honest, reasonable estimate is far better than tagging the whole receipt to one job — precision to the penny matters less than avoiding a number that's flat-out wrong for one of the two jobs.
Does this apply to fuel and mileage too?
Yes — a fuel stop or a single day's driving between multiple sites has the same problem, and the same fix: allocate by the trip actually done for each job rather than dumping it all on one.