You've done the work, the client is in another country, and now the invoice has to say an amount. The awkward part isn't the template. It's that two currencies are involved and two dates are involved, and the number you booked on the first date is almost never the number that arrives on the second.
People have been asking some version of “what exchange rate do I use when invoicing customers abroad?” for about as long as freelancers have had foreign clients. The short answer is that the rate on the invoice matters less than people think, and the rate on the day you're paid matters more. Here's why, on real numbers.
The same job, on real rates, two ways #
Take one job, invoiced on 1 September 2026 and paid on 6 November 2026. The rates below are the European Central Bank's published reference rates for those two days: 1.1590 dollars per euro on 1 September, 1.1165 on 6 November.
If your books are in euros and you invoiced a US client USD 5,000:
| rate | in your books | |
|---|---|---|
| Invoice issued, 1 Sep | 1.1590 | EUR 4,314.06 |
| Payment received, 6 Nov | 1.1165 | EUR 4,478.28 |
| Difference | EUR 164.22 gain |
If your books are in dollars and you invoiced a European client EUR 5,000:
| rate | in your books | |
|---|---|---|
| Invoice issued, 1 Sep | 1.1590 | USD 5,795.00 |
| Payment received, 6 Nov | 1.1165 | USD 5,582.50 |
| Difference | USD 212.50 loss |
Same two dates, same move in the rate. The dollar strengthened a little over nine weeks, so whoever was owed dollars came out ahead and whoever was owed euros came out behind. Nobody discounted anything or made a mistake. And nothing about the work changed.
That's the whole problem in one picture. The question is what to do about it.
Decide which currency the invoice is in #
An invoice is denominated in one currency. That's what the client owes, what the contract should name, and what the total is in. A second currency on the page is a note for your own books, not part of the debt.
The choice moves the risk you just saw:
- Invoice in your own currency and you know exactly what you'll get. The client carries the rate risk, and their bank converts at whatever rate it likes.
- Invoice in the client's currency and it's easier for them to approve and pay, which does get invoices paid faster. You carry the risk, as in the tables above.
Neither is right in the abstract. A one-person business billing a large company usually does better invoicing in the client's currency, because it removes one reason for accounts payable to bounce it. A large invoice on 60-day terms between two currencies that have been moving a lot is a different calculation.
What you shouldn't do is leave it ambiguous. Write the ISO code next to the
total: USD, EUR, CAD, GBP. The $ sign alone is used by more
than twenty currencies, and “$2,000” has started more than one argument.
Which rate goes on the invoice #
If you invoice in the client's currency and keep books in yours, you'll want the amount in your own currency too. This is the number people worry about most, and it deserves the least worry. It records what the invoice was worth on the day you issued it. It isn't a promise to anyone.
Two rules cover nearly all of it:
- Pick one source and stick to it. A central bank's daily reference rate (the ECB for euros, your own central bank otherwise) or your accounting tool's rate for the invoice date. Which source matters far less than not switching to whichever one flatters the month.
- Write down which source you used. Six months on, when something doesn't tie out, the question will be “where did 1.1590 come from?”, and the answer shouldn't be a guess.
Some countries say which rate is acceptable, particularly for VAT. That's a question for your own tax authority's guidance, not for a blog post, this one included.
Booking the difference #
In accrual books, the two numbers in each table are two different things:
- Revenue is what you earned when you issued the invoice: EUR 4,314.06 in the first table, USD 5,795.00 in the second.
- The difference at payment is an exchange gain or loss, a line of its own.
Keep them apart. If you just record whatever landed in the bank as revenue, your income becomes a blend of what you charged and what the currency market did over nine weeks, and “am I charging enough?” gets harder to answer. In a year when the rate runs against you, revenue looks smaller than the work you actually sold.
If you file on a cash basis, it's simpler: you generally record what arrived, at the rate on the day it arrived. How an exchange gain or loss is taxed, and whether it's taxed at all, depends on where you file, and that one really is for an accountant in your country.
The money that goes missing in between #
The exchange move isn't the only reason the amount that lands is short. There are two more, and they're worth telling apart before you email anyone:
- The spread. The gap between the reference rate and the rate the bank actually gave. It never shows up as a line item, which is why it's usually the biggest of the three.
- Fees. The visible transfer fee, plus intermediary bank charges taken in transit on wire transfers, often without warning. That's the usual reason a payment arrives short by an odd number nobody can explain.
If an invoice arrives short, check the intermediary charges before you write to the client. It's often not their doing. You can put “all bank charges borne by the payer” in the contract, but it has to be there before the invoice, not added after.
A short checklist for the invoice itself #
- The currency as an ISO code, at least on the total
- Your legal or business name and address, and the client's legal entity name (not the trading name, and not the person who briefed you)
- A sequential, unique invoice number
- Issue date, and a due date written as a date rather than “net 30”
- Bank details in the format the payer's bank expects: IBAN and BIC for Europe, routing and account number for the US. They aren't interchangeable
- Where VAT applies, the treatment you're using and the client's registration number if it's part of that treatment
- Optional on the page, useful in your records: the amount in your own currency and the rate source
Where Mini Accountant fits #
This is Mini Accountant's blog, so here's the honest version of how it handles this. Each customer has their own currency, and their invoices use it. Every payment keeps its own exchange rate into your business currency, either fetched for its date or typed in from your bank statement, so the totals and reports add up in one currency. Every feature is free on iPhone, iPad, Android and the web; the optional Pro subscription removes the “Powered by Mini Accountant” line from invoices and reports.
Where something else is the better answer: if you need full double-entry bookkeeping with an audit trail, payroll, or a specific national e-invoicing format, look at the established accounting packages. And if you send one foreign invoice a quarter, a template and a spreadsheet with the ECB rate pasted in are honestly fine.