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Bookkeeping for Airwallex, Wise, Mercury and Revolut Business: What Changes When Your Bank Is a Platform

By Di Ma, Project Manager 08 SEP 2026 · 9 MIN READ

A growing share of the companies we keep books for have never walked into a bank branch. They collect in USD through Airwallex, pay European suppliers from a Wise balance, hold a Mercury account because their investors are American, and issue Revolut cards to a team spread across three time zones. It works beautifully for running the business. It also quietly breaks the bookkeeping habits that were designed for one bank, one currency and one monthly statement.

This is a practical guide to what changes. None of it is exotic accounting; all of it is easy to get wrong when the ledger is set up as if a fintech login were a bank account.

Five ways a platform account is not a bank account

• One login holds many currencies. An Airwallex or Wise account is really a set of balances, one per currency, each with its own statement. Revolut Business works the same way. Mercury is the exception in this group: US-dollar accounts provided through partner banks.
• Conversions happen inside the account. Selling USD for HKD never leaves the platform. There is no counterparty bank, just a debit to one balance and a credit to another at the platform's rate.
• Cards draw straight from the balance. Platform cards are debit-style. There is no statement cycle and no card liability to settle; every card swipe is a bank line the moment it settles.
• Fees hide inside the line. Some platforms show the conversion fee separately; others price it as a margin inside the rate. Payment-acceptance settlements arrive net of the platform's cut.
• Money can be held, reserved or pending. Card authorisations that have not settled, rolling reserves on payment collection, and incoming payments still clearing all sit between "in the account" and "yours to spend".

One balance, one ledger account

The single most useful design decision: the ledger account is the currency balance, not the login. A company that holds HKD, USD and SGD in Airwallex and EUR and GBP in Wise has five bank accounts in the chart of accounts, not two:

• 1010 Airwallex — HKD
• 1011 Airwallex — USD
• 1012 Airwallex — SGD
• 1020 Wise — EUR
• 1021 Wise — GBP

Each one carries its own currency, reconciles to its own statement, and is revalued on its own at period-end. Collapse them into a single "Airwallex" account in the functional currency and three things go wrong at once: conversions turn into phantom gains and losses, the statement no longer ties to anything in the ledger, and your auditor cannot confirm a balance that does not exist on any document.

Recording a conversion properly

Say the functional currency is HKD, the USD balance is carried at 7.80, and you convert USD 10,000 at the platform's rate of 7.79. The entry is: credit Airwallex USD 10,000 (HKD 78,000 at book rate), debit Airwallex HKD 77,900, and the HKD 100 difference goes to realised exchange loss. Where the platform shows a separate fee line, as Wise does, the fee goes to bank charges and the rate difference stays a pure exchange result. Where the margin is inside the rate, the exchange line absorbs it. Both are correct; mixing the two methods across a year is not.

One thing to know if you export raw transaction data rather than statements: a single conversion can arrive as several rows per currency, typically a hold, a release and a settlement, sharing one reference. They net to one movement per currency and should be booked as one journal. Posting each row individually is the commonest way a fintech ledger ends up with balances that are right in total and wrong in every account.

Cards are not credit cards

With a traditional corporate card the statement is a liability, paid once a month, and the bookkeeping has a natural checkpoint. Platform cards have none of that. Each purchase debits the currency balance when it settles, which can be a day or two after the authorisation you see in the app, and it lands in the books as an ordinary bank line that needs a receipt like any other. Two habits keep this manageable:

• Name the cards. A virtual card per vendor, project or client puts the purpose in the transaction description before anyone has to guess. A card issued for a client's subscriptions is a recharge to that client, not your IT expense, and the card name is how the bookkeeper knows.
• Capture the receipt at the point of spending. Card lines are small, frequent and forgettable. A photo from the phone the same day beats a reconstruction at month-end every time.

Money coming in: settlements, reserves and collection accounts

If you accept card or wallet payments through the platform, what arrives is a settlement: the customer's payments for the day, less the platform's fee, sometimes less a rolling reserve. Three rules keep the receivables ledger honest. Clear the customer's invoice at the invoice amount, never at the settled amount. Book the platform's fee to bank charges. If you add your own card surcharge on top, that surcharge is your income, not a reduction of the fee.

A reserve held by the platform is already inside your account balance. It is not a separate receivable; at most it is a note on liquidity, and a disclosure point if it is material at year-end.

Global collection accounts, the local account numbers a platform gives you in other countries, receive whatever anyone sends to them. Not every receipt is a customer paying an invoice. Check the payer before clearing anything against receivables; referral commissions, refunds from suppliers and a director topping up the account all arrive through the same door.

Payouts from Stripe, PayPal or Shopify into the platform follow the same logic one level up: the payout is net of processor fees and refunds, so the gross sales, fees and refunds come from the processor's payout report, and the bank line only clears a processor clearing account.

Reconciling a platform account

Reconcile each currency balance monthly against the platform's own statement for that currency. The closing balance on the statement must equal the ledger; timing items are card authorisations not yet settled, conversions in flight, and incoming payments still pending. Airwallex, for instance, suggests waiting a couple of business days before pulling its reconciliation report so that pending items settle first.

Download and file the monthly statements even if your books are fed by an API. Some platform endpoints keep only weeks of history, and the statement PDF, not the API, is what an auditor accepts as evidence. The feed is for keeping the books current; the statement is for proving them.

What your auditor will ask

• Statements for every currency balance for the whole year, and reconciliations for each at year-end.
• Confirmation of the year-end balances, either a confirmation request sent to the platform or a dated balance statement the auditor accepts.
• What kind of institution holds the money. Depending on the country, a platform may be a bank, or a licensed payment or e-money institution that safeguards client funds rather than taking deposits. Balances are normally presented within cash and cash equivalents, but the classification, and any disclosure of restricted reserves, is a conversation to have with the auditor before the statements are drafted.

How we run it at Certanta

Accounts we connect directly, Airwallex among them, are synced every morning; platforms and traditional banks we do not connect yet join by statement upload and are reconciled into the same ledger. Every currency balance is its own ledger account. Conversions are collapsed to a single entry at the executed rate, and transfers between your own accounts are routed through a clearing account so nothing is counted twice. Every proposed entry is reviewed and approved by a dedicated human bookkeeper before it posts, receipts arrive from your phone, and the monthly statements serve as the check on the feed rather than the input to the books.

Frequently asked questions

This article is general information, not advice for your specific situation. Accounting treatment and disclosure depend on your reporting framework and jurisdiction; talk to your accountant or auditor, or to us.