Petty cash (construction)
Petty cash solves a practical problem on the jobsite: there are small, urgent expenses — a freight charge, a bucket of paint that ran short, screws and fasteners, water for the crew — that cannot wait for a requisition and a purchase order to be issued. Instead of stopping the work, a fixed fund is handed to the site supervisor or foreman, who covers those expenses and backs up every outlay with a voucher or receipt.
Control rests on two ideas: a maximum amount per expense and full documentation. Each disbursement is recorded with a voucher (who requested it, what for, how much) along with its receipt or invoice; at any moment the cash on hand plus the vouchers and receipts must equal the assigned fund. When the fund runs low, a reconciliation is done, the receipts are handed in, and it is topped back up to the original amount (imprest fund). Large or plannable expenses do not go through petty cash: they are channeled through a requisition and a purchase order, which give better traceability and better prices.
One important point is the tax angle: for an expense to be deductible and its recoverable tax (VAT or equivalent) creditable, it generally needs a valid tax invoice issued in the company's name and, above the threshold set by law, to be paid by means other than cash (bank transfer, card, or a nominative check). Many petty cash expenses are paid in cash and backed only by a simple receipt, so they are often non-deductible and become pure cost. That is why it pays to keep petty cash limited to what is minor and essential, and to request a proper invoice whenever possible.
Example
A project is assigned petty cash of $10,000 as an imprest fund. During the week it pays $1,200 in freight, $850 in hardware, and $600 in consumables, each with its voucher and receipt. At reconciliation, $7,350 remains in cash plus $2,650 in receipts = $10,000. The receipts are handed to accounting and the fund is replenished back to $10,000.
| Order | Supplier | Material | Amount | Delivery | Status |
|---|---|---|---|---|---|
| OC-2026-0148 | THThe Home Depot | Concrete f'c=250 | $184,000 | Lun 30 | In transit |
| OC-2026-0147 | CConstrualcalde | Rebar #4 | $96,000 | Lun 30 | Approved |
| OC-2026-0146 | CConstrurama | Red brick | $71,400 | Mar 1 | Delivered |
| OC-2026-0145 | CConstrualcalde | Gray cement | $28,000 | Dom 29 | Delivered |
| OC-2026-0144 | SSodimac | Electrical | $42,500 | Vie 27 | Delivered |
Frequently asked questions
What is petty cash used for on a construction site?
To cover minor, urgent, or unforeseen expenses that do not justify a formal purchase process: freight, last-minute hardware, consumables, per diems, or small repairs. It keeps the project from stalling over a small disbursement.
What is the difference between petty cash and a purchase order?
Petty cash is money for small, immediate expenses, controlled with vouchers and receipts. A purchase order is the formal document used to buy planned materials from a supplier, with quoted prices and payment terms. Large or plannable expenses should go through a purchase order, not petty cash.
Are cash petty-cash expenses tax-deductible?
Not always. To deduct an expense and credit its recoverable tax, you generally need a valid tax invoice in the company's name and, above a certain amount, a payment made by means other than cash. Many petty cash expenses are paid in cash with only a simple receipt, so they are often non-deductible and turn into cost. This is general information, not tax advice; confirm it with your accountant.