What it means
Under an imprest system a department is given a fixed float, say $500. As money is spent, receipts accumulate in place of cash, so at any moment the cash on hand plus the vouchers should add back to $500.
That fixed ceiling is what separates an imprest from simply keeping some cash in a drawer. Reimbursement then restores the float rather than issuing some convenient new amount.
If $380 of receipts are submitted, exactly $380 is paid back into the tin, which returns it to $500 and keeps the ceiling on exposure fixed. The float therefore has a memory, because it always comes back to the same number.
The control value is that the float itself becomes the reconciliation. Any shortfall is immediately visible without tracing individual transactions, and the maximum a business can lose from one float is capped at its fixed size.
Auditors can test a whole network of floats in an afternoon by counting cash and adding vouchers. The accounting treatment is simple and often misunderstood.
The float is set up once as an asset, and no expense is recorded when petty cash is spent; expenses are recognised when the receipts are processed at reimbursement, which is when the general ledger finally sees them. This also stops the same receipt being claimed twice, because the voucher leaves the tin when it is processed.
Imprest thinking extends well beyond cash tins. Prepaid company cards, branch bank accounts, site advances for engineers and even consumable stock kits can all run on a fixed replenished float with exactly the same discipline.
The principle is identical in each case: fix the amount, demand evidence, then restore the amount. The common variant is a fluctuating or non-imprest float, where whatever seems convenient is topped up without restoring a set amount.
It is easier to administer and considerably weaker as a control, which is why auditors prefer the imprest version. Non-imprest floats also make loss harder to spot, because there is no expected balance to test against.
In practice
Real-world examples.
Example
A construction firm gives each site manager a $1,000 imprest for consumables and emergency parts. Receipts are submitted weekly and the float is restored to $1,000, so head office knows its maximum exposure is $1,000 per site.
Example
A dental practice keeps a $300 petty cash imprest for postage, milk and taxi fares. The practice manager counts cash and vouchers every Friday, and any difference is investigated the same day rather than at year end.
Example
A charity issues prepaid cards to outreach workers with a $250 monthly imprest each. Spending is coded from the card statements and each card is reloaded back to $250, giving the finance team a fixed and predictable control total.
Formula
Calculation
Reimbursement required = Imprest amount - Cash remaining
Expected cash = Imprest amount - Total vouchers held
A branch office runs a $500 imprest petty cash float. At month end the tin holds $118 in cash and vouchers totalling $382.
Check: $118 + $382 = $500, so the float reconciles exactly.
Reimbursement required = $500 - $118 = $382, which restores the float to $500.
Had the tin held only $110, expected cash would be $500 - $382 = $118, giving a shortfall of $8 to be investigated and, if unexplained, written off to a cash difference account.Case study
Seen in the real world.
Kestrel Field Services is a fictional, illustrative maintenance company with eleven regional depots, each holding petty cash. Depots simply asked head office for money when they ran low, and the amounts they held drifted between $200 and $2,400 with no ceiling at all.
An internal review found $1,900 of unsupported withdrawals across three depots and, more troubling, no quick way to tell what any depot should be holding. The finance director moved every depot onto a $600 imprest, reimbursed only against submitted vouchers.
Within two months a reconciliation that used to take a day took under an hour, because each depot only had to prove that cash plus receipts equalled $600. The illustrative point is that the control came from fixing the amount, not from counting harder.
Watch out
Common mistakes.
- Topping the float up to a round number instead of reimbursing the exact value of the receipts. That breaks the arithmetic that makes an imprest self-checking.
- Posting petty cash spending to expense as it happens. Expenses are recognised when vouchers are processed at reimbursement, otherwise the ledger and the tin drift apart.
- Setting the float far larger than genuine monthly need. An oversized imprest increases the amount at risk and quietly encourages spending that should go through purchasing.
Questions
People also ask.
What size should an imprest float be?
Roughly one reimbursement cycle of normal small spending, so a site spending about $400 a month with monthly top-ups needs a float near $500, not $2,000.
Is an imprest only for cash?
No, the same fixed-and-replenish logic works for prepaid cards, branch bank accounts, fuel accounts and consumable stock kits.
What happens if the float does not reconcile?
Investigate the difference, write off genuinely small unexplained amounts to a cash difference account, and escalate anything that repeats or is material.
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