The small box that causes big headaches
Petty cash feels too trivial to think about — a drawer with some bills for stamps, parking, and the occasional emergency coffee run. But that casualness is exactly why it quietly corrodes the books. Cash that leaves without a record can't be reconciled, can't be deducted, and can't be defended. The fix isn't to ban petty cash; it's to run it with one simple, time-tested discipline so the box is always reconcilable and every dollar is accounted for. This guide covers how to set it up, log it, and reconcile it.
This is general education, not accounting or tax advice — confirm the specifics for your business with a professional.
Use the imprest system
The standard, bulletproof way to run petty cash is the imprest system, and it rests on one rule: the fund is always fixed at a set amount.
You decide on a float — say $200 — and that's the fund's permanent size. At any moment, the cash in the box plus the receipts in the box should add up to exactly $200. Spend $35 on supplies, and now you have $165 in cash and $35 in receipts — still $200 total. When the cash runs low, you replenish back to $200 by writing one check (or transfer) for the exact total of the receipts. That single replenishment is what posts the real expenses to your ledger.
The imprest rule is the whole trick: because the total never changes, any shortfall is immediately visible.
Set it up cleanly
- Pick a float that fits your real spending — enough to last a couple of weeks of small purchases, not so much that a lot of cash sits idle and at risk. Most small businesses land between $100 and $300.
- Fund it with one transaction. Write a check or transfer to "Petty Cash." In your books this moves money from your bank account into a Petty Cash asset account in your chart of accounts — it's not an expense yet, just cash in a different location.
- Assign one custodian. A single person is responsible for the box. This is basic segregation of duties: one accountable person, not a free-for-all.
Log every single disbursement
Every time cash leaves the box, two things happen: a receipt goes in, and a petty cash slip records it. The slip notes the date, amount, what it was for, and who took it. No receipt, no cash — that's the rule that keeps the system honest.
This matters beyond tidiness. Those receipts are what let you categorize the expenses correctly at replenishment time, and they're the support that makes the spending a legitimate, deductible business cost rather than an untraceable hole. A drawer of unlogged withdrawals is exactly what an auditor — or a lender — flags first.
Reconcile before every replenishment
Reconciling petty cash is quick because of the imprest rule. Before you top the fund back up:
- Count the cash in the box.
- Add up the receipts and slips.
- Cash + receipts should equal the float. If $200 of float shows $158 in cash and $40 in receipts, you're $2 short — a small discrepancy to note and investigate, not ignore.
- Replenish for the receipt total ($42 in this example, rounding the variance into a cash-over/short account), bringing cash back to $200 and posting those expenses to the ledger.
That cash-over/short line, watched over time, is a quiet honesty check. A few cents here and there is normal; a persistent or growing gap is a control problem worth addressing.
Fold it into the monthly close
Petty cash reconciliation belongs on your month-end close checklist right alongside bank reconciliation — same principle, smaller scale: the recorded balance must tie to what's physically there. Do it every month and the petty cash box stops being the one account nobody trusts. Hosting Books gives petty cash its own tracked account so the float, the disbursements, and the replenishments all reconcile against the ledger like any other cash account.
This article is general information, not accounting or tax advice. How you handle and deduct cash spending depends on your facts — confirm with a qualified professional.