Foreign-Currency Credit Card Expenses: A Processing Guide

Why Foreign-Currency Expenses Need Special Treatment

When an employee swipes a corporate credit card in a foreign currency, the transaction does not stay in that currency forever. At some point the amount must be converted into your company's functional currency — the main currency used in your books. In Japan, that is typically the Japanese yen (JPY).

The challenge is that exchange rates move every day. A USD charge made on Monday will convert at a different rate than the same charge made on Friday. If everyone on a team uses a different rate to record expenses, your accounts will be inconsistent and your tax filings may be challenged. Getting the methodology right from the start saves significant correction work later.

Which Exchange Rate Should You Use?

Japanese corporate tax rules address this directly. Corporate Tax Basic Directive 13-2-1-2 specifies how foreign-currency transactions should be converted for tax purposes. In practice, companies are generally permitted to use either the spot rate (the rate on the actual transaction date) or an authorised average rate — most commonly the monthly average rate published by the Tax Administration Japan (NTA) or a rate derived from a widely used reference source.

The key principle is consistency: whichever method you choose, you must apply it uniformly across all similar transactions in the same accounting period. Switching between spot rates and monthly averages transaction by transaction is not acceptable.

For the period 28 April 2026 to 28 May 2026, the data illustrates why this matters:

• The JPY/USD monthly average was approximately 158.26 JPY per USD (inverted from the average rate of 0.00631864), while the rate at period-end reached 159.49 JPY per USD.
• The JPY/EUR monthly average was approximately 184.80 JPY per EUR, with the period-end rate at 185.19 JPY per EUR.

A company recording USD expenses only at the end-of-period rate would consistently overstate those expenses compared with one using the monthly average — a difference of roughly 1.23 JPY per USD across every transaction.

A Concrete Calculation Example

Suppose a business traveller charges USD 450 to a corporate card during a business trip that falls within the April–May 2026 window.

A 554 JPY difference on a single USD 450 charge may look small, but scale that across a sales team making dozens of overseas purchases per month and the cumulative variance becomes material. For a team recording 100 such transactions monthly, the gap between methods would be approximately 55,400 JPY — enough to affect reported profit and, consequently, taxable income.

The same logic applies to EUR transactions. A EUR 300 hotel charge recorded at the monthly average of 184.80 JPY/EUR equals 55,440 JPY, whereas using the period-end rate of 185.19 JPY/EUR gives 55,557 JPY — a 117 JPY difference per transaction.

Step-by-Step Processing Workflow

Follow these steps to keep foreign-currency credit card expenses clean and audit-ready:

1. Collect the original receipt in the transaction currency (e.g., USD, EUR) with the transaction date clearly shown.
2. Identify the approved conversion rate for that date or accounting period, consistent with your company's policy and Directive 13-2-1-2.
3. Convert the foreign amount to JPY using that rate and record both the original amount and the JPY equivalent in your expense report.
4. Note the source of the rate (e.g., "NTA monthly average for May 2026") so auditors can verify it without guesswork.
5. Reconcile against the card statement, which will show the rate the card issuer actually applied. Any difference between your policy rate and the card issuer's rate may generate a small foreign exchange gain or loss that must be recorded separately.
6. Retain documentation for at least seven years, consistent with Japanese record-keeping requirements.

Common Mistakes to Avoid

• Using the card issuer's rate as your accounting rate without a documented policy. Card networks apply their own spread and that rate may not qualify as an "authorised" rate under Directive 13-2-1-2.
• Mixing rate methods — using spot rates for USD transactions but monthly averages for EUR transactions without a policy rationale.
• Ignoring exchange-rate fluctuation adjustments at period-end. If you carry a payable in foreign currency on your balance sheet, it may need to be remeasured at the closing rate.
• Losing the original foreign-currency receipt. Tax authorities typically want to see both the source amount and the converted figure.

Disclaimer: This article explains general practice based on publicly available Japanese tax directives; consult a qualified tax professional for guidance specific to your company's situation.

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Zenrate can help you track the exact daily and monthly average rates for JPY/USD, JPY/EUR, and many other currency pairs, so your expense reports are always built on documented, consistent data — exactly what auditors expect.

References

• Corporate Tax Basic Directive 13-2-1-2 (Japan): https://www.nta.go.jp/law/tsutatsu/kihon/hojin/13_02/01.htm