Expats and Travel
How to Track Expenses in Multiple Currencies
Earn in one currency, pay rent in another, travel in a third, and a simple spreadsheet starts producing numbers that mean nothing. This guide shows how to track expenses in multiple currencies so that totals stay honest, the cost of conversion becomes visible and a weak month in one currency does not look like overspending.
Step 1: Choose One Base Currency
Your base currency is the one all totals and budgets are shown in. Pick the currency you think in: usually the one you are paid in, or the one your largest fixed costs are in. If you earn in euros and spend most of your money in Thailand, either can work; what matters is that you do not change it every month, or your history stops being comparable.
Step 2: One Account per Real Balance
Create a separate account for every balance in its own currency: a euro card, a dollar account, a pound account at a multi-currency bank, local cash. Do not merge a euro card and a dollar balance into one “bank” account. Each account keeps its own currency, and its balance should always match what your bank shows.
Step 3: Record What Actually Left the Account
When you pay 1,200 baht with a euro card, two numbers matter: the price (1,200 THB) and what the bank debited (for example €31.40). Record the expense against the card in euros at the amount the bank charged, and keep the original price for reference. The bank's figure already includes its exchange margin, so your balances keep matching the bank.
That margin is worth noticing. If the mid-market rate made 1,200 THB worth about €30.90, the hidden cost of that payment was €0.50, roughly 1.6%. Across a month abroad, these margins add up to a real line in your budget.
Step 4: Treat Exchanges as Transfers, Not Spending
Moving money between your own currencies is not an expense. When you convert €500 to $540, record a transfer from the euro account to the dollar account, with the amount that arrived on the other side. If the provider charged a separate fee, record it as its own expense in a “Bank fees” category. That way spending reports show what you bought, and fees show what moving money cost you.
An ATM withdrawal abroad works the same way: a transfer from the card account to a local cash account, plus the ATM fee as an expense.
Step 5: Convert at the Date of the Expense
To show totals in your base currency, every expense has to be converted. Use the rate on the day of the expense, not today's rate. If you sum last spring's dollar expenses at today's rate, past months change every time the rate moves, and you see “overspending” that never happened. Converting at the date fixes each month's total once.
Step 6: Budget in the Base Currency
Set category budgets in your base currency. If your rent is in a different currency, expect the base-currency amount to move a little with the rate, and leave a small buffer for it rather than adjusting the budget every month.
Common Mistakes to Avoid
- Counting a conversion as income or spending. Your net worth did not change when you bought dollars with euros, apart from the fee.
- Using the card's price instead of the bank's debit. The price in baht is not what left your account; the balance drifts away from the bank within weeks.
- Forgetting cash. Local cash is a balance in its own currency. Without a cash account, every withdrawal looks like one large unexplained expense.
Doing This in Amon Budget
Amon is a multi-currency budget app built around these rules:
- Accounts in several currencies and a base currency for totals, set in Settings.
- Paying in a foreign currency: you can change the currency of a transaction. When it differs from the account's currency, Amon shows both amounts, and you can correct the account amount to what your bank actually charged.
- Converted at the time of entry: each transaction stores its value in the base currency when you save it, so past totals do not shift with today's rate.
- Transfers between currencies: a transfer between accounts in different currencies shows how much the receiving account gets. Fresh exchange rates need a connection.
Travelling without mobile data? Everyday budgeting keeps working: see offline expense tracking.
Frequently Asked Questions
Which base currency should I choose?
The one you think in, usually the currency you are paid in or the one your biggest fixed costs are in. Keep it stable so months stay comparable.
How do I record a currency exchange in a budget?
As a transfer between your own accounts, from the currency you sold to the currency you bought, with the amount that arrived. Record any separate fee as its own expense.
Why do my past totals change when exchange rates move?
Because they are converted at today's rate. Convert each expense at the rate on its date and keep that value, so past months stay fixed.