Petty Cash for a Small Company: The Imprest System, Vouchers and Bookkeeping

By Di Ma, Project Manager 29 OCT 2026 · 4 MIN READ

Most small companies still need a little cash: a courier who wants paying at the door, a taxi, cleaning supplies, coffee for a client meeting. Petty cash is the small float kept for those payments. It's also, in many small companies, the least-kept account in the books. A simple system fixes that.

The imprest system

The usual way to run petty cash is the imprest system:

Set a fixed float, say HK$3,000: enough for a month of small payments, not more.
Every payment gets a voucher, with its receipt attached.
At any time, cash plus vouchers equals the float. That's the check.
Top up by exactly what was spent, by a withdrawal or transfer from the bank, bringing the cash back to the float.

Because the float never changes, any difference between cash plus vouchers and the float is visible straight away, and the top-up cheque or transfer is backed by the vouchers it replaces.

The petty cash voucher

A voucher can be a printed slip or a line in an app. Each one records:

the date and amount;
what it was for, and the supplier;
who took the cash, and who approved it;
the receipt attached, or a note of why there isn't one (see lost receipts).

Set a limit per payment, for example HK$500. Anything bigger goes through the bank or a company card.

Count, reconcile and top up

Count the cash at least monthly, at the month end, and whenever the person holding it changes.
Add up the vouchers since the last top-up. Cash plus vouchers should equal the float.
Top up by the voucher total, and book the vouchers.
A small difference goes to a "cash over and short" line, with a note. A large or repeated one is a question to ask.

The bookkeeping

A HK$3,000 petty cash float for one month (illustrative)
When	Entry
Float set up	Dr Petty cash 3,000 Cr Bank 3,000
Month's vouchers	Dr Travel 860, Postage and courier 420, Cleaning 610, Staff refreshments 750 Cr Petty cash 2,640
Top-up from the bank	Dr Petty cash 2,640 Cr Bank 2,640

Petty cash is an asset account like a bank account. Each voucher is booked to the expense it was for, not to a single "petty cash expenses" line, so the income statement shows what was actually spent. After the top-up, the petty cash account is back at HK$3,000, and it should equal the cash in the box on any count.

The Certanta client portal, cash flow page for the fictional demo company Harbourfront Trading Ltd: cash today per account, a Hang Seng Bank HKD current account, a USD savings account translated to HKD, and petty cash, with the totals for money in and out over 13 weeks. — Petty cash as its own account, next to the bank accounts, in the demo company's cash view.

Simple controls

One person holds the cash, in a locked box.
Someone else approves the top-up and checks the vouchers.
No IOUs and no personal loans from the box. No cash income goes into it either: takings are banked separately.
A surprise count now and then.

Auditors look at petty cash for the same reason everyone else does: it's cash with little paperwork. A float that always reconciles, with a receipt for each voucher, is a quick item on their list (see the audit process).

Do you need petty cash at all?

Many small companies don't. A company card or a prepaid expense card covers most of what petty cash used to, with a statement line for every payment. For staff who pay out of their own pocket, a simple expense claims process works better than handing out cash. Keep a float only for the payments that really need cash.

How Certanta handles petty cash

Petty cash as its own account, shown with your bank accounts in your portal.
Receipts uploaded from a phone, in any language, and booked to the right expense as drafts your bookkeeper approves.
Top-ups matched to the bank withdrawal or transfer, as a movement between your own accounts (see own-account transfers).
The balance checked against your count as part of the month-end close (see the month-end close).

Frequently asked questions

What is the imprest system for petty cash?

A fixed float, for example HK$3,000, from which small payments are made against vouchers. At any time the cash plus the vouchers equals the float, and the float is topped up by exactly the amount spent.

How much petty cash should a small company keep?

Enough for about a month of small cash payments and no more. Many small companies keep a few thousand Hong Kong dollars or less, and pay anything larger by bank transfer or card.

How is petty cash recorded in the books?

As an asset account like a bank account. Setting up or topping up the float moves money from the bank into petty cash; each voucher is booked to the expense it was for, reducing petty cash.

How often should petty cash be counted?

At least once a month, at the month end, and whenever the person responsible for it changes. An occasional surprise count is a good control.

What if petty cash does not balance?

Recount and check the vouchers first. A small difference can be booked to a cash over and short account with a note; a large or repeated difference should be investigated.

Is a company card better than petty cash?

For most purchases, yes: every payment appears on a statement and needs no cash handling. Petty cash is still useful for the few payments that can only be made in cash.

Petty cash that adds up

Certanta keeps petty cash as its own account in your books: receipts uploaded from a phone, each top-up matched to the bank, and the balance checked against the count.

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This article is general information about bookkeeping, not accounting or tax advice. The right float and controls depend on your business.