What is base currency?
It is the common currency used for company-level accounting and financial reporting.
Lynka guide
What is multi-currency accounting?
Multi-currency accounting records the currency used in a sale or purchase while also translating it into the company’s base or functional currency for reporting. The original amount, exchange rate and accounting value stay connected.
A quote, invoice, purchase order or supplier bill may be denominated in one currency while the business reports in another. The transaction currency is what the customer or supplier sees; the base or functional currency is the common currency used for the company’s books.
For example, a 1,000 EUR invoice can remain a 1,000 EUR customer obligation while the accounting record also stores its USD equivalent using the rate selected for the relevant date. If the rate changes before payment, accounting has to explain that difference rather than rewrite the original invoice.
01
Choose the reporting base currency deliberately
The base currency is the common reporting currency used to compare transactions across the business. Changing it after meaningful financial activity has begun can make historical comparisons difficult.
Treat the base-currency choice as an accounting setup decision rather than a display preference.
02
Keep the transaction currency visible
Customer invoices and supplier bills should preserve the currency in which the commercial obligation was created. The customer may owe 1,000 EUR even though the company also needs a USD equivalent for reporting.
Do not replace the original currency with a converted number and throw away the commercial amount the counterparty actually sees.
03
Use a dated exchange rate
Exchange rates change over time. The rate used for a transaction should correspond to an appropriate effective date under the business’s accounting policy.
Keeping the date and rate together makes later review possible when the base-currency total differs from what someone gets using today’s rate.
04
Preserve purchasing currency assumptions
A supplier purchase order can be created in the supplier’s currency. Preserving the relevant rate context helps the business compare the order, receipt, supplier bill and eventual payment without silently moving the commercial baseline.
This is particularly useful when goods are received before the supplier is paid.
05
Payment can create a realized FX difference
Suppose an invoice is recorded when 1 EUR equals 1.10 USD, then paid when the rate has moved. The base-currency value of the settlement may differ from the base value of the original receivable or payable.
That difference belongs to foreign-exchange accounting, not to a manual edit of the original invoice.
06
Reports need a common currency
Financial statements need a consistent reporting basis even when sales and purchases occur in several currencies. Base-currency values provide that common view while the transaction records preserve their original currencies.
Operational reports should label currency clearly so teams do not add unrelated currencies together as if they were the same unit.
07
Separate realized and unrealized FX differences
A realized FX difference is recognized when a foreign-currency receivable or payable is settled and the base-currency value differs from the amount originally recorded.
An unrealized FX difference is a reporting-date adjustment on an open foreign-currency balance that has not been settled yet. Whether and how to revalue open balances depends on the accounting policy and jurisdiction, so the report should show the rate and date used rather than hiding the assumption.
08
Do not treat currency conversion as a cosmetic feature
Multi-currency affects pricing, customer balances, supplier obligations, payments and accounting. Common mistakes include losing the original transaction amount, applying today’s rate to an old transaction, mixing currencies in a report without conversion, and treating an open-balance revaluation as a settled payment difference.
The business should define which currencies it accepts and how rates are maintained.
If the business needs complex hedging, consolidation or specialist treasury accounting, evaluate dedicated financial requirements rather than assuming ordinary transaction conversion covers them.
Multi-currency checklist
- Base currency chosen deliberately.
- Allowed sales and purchasing currencies defined.
- Transaction currency preserved on commercial records.
- Exchange rates have effective dates.
- Base-currency values can be traced to the rate used.
- Payment-date FX differences are reviewed separately from price changes.
- Reports do not add unrelated currencies without conversion.