Setting a Custom FX Rate for Your Company

#What a custom rate does

A custom rate (an "FX rate override") pins the conversion rate for one currency, for one month, across your whole company. Once set, every flow that converts that currency — bills, sales invoices, payments, bank reconciliation, expenses, credit notes, purchase-order matching, and the month-end FX revaluation — uses your rate instead of the market rate.

#How to set one

There is no self-serve screen in this version — to set a custom rate, contact Light support with:

• Currency — the currency you want to pin (e.g. USD, GBP, CZK). It must not be EUR (see below).
• Rate — expressed as how much one unit of the currency is worth in EUR. For example, "1 CZK = 0.04 EUR." This is the same direction Light shows rates elsewhere.
• Month — the month the rate applies from.

Support will confirm the rate back to you before it takes effect.

Self-serve setup from your organization settings is planned for a future release.

#How custom rates behave

• Monthly. One rate per currency per month. A rate can't change part-way through a month — set a new rate for the next month instead.
• Forward-looking. A rate applies to transactions dated on or after the 1st of its month. Already-posted journal entries are never recalculated, so closed periods don't move.
• EUR is the reference currency. You give each currency's value in EUR, and Light derives the cross-rates between your currencies from that. EUR itself can't be overridden — it's the anchor.
• Set every currency you use. For a conversion between two non-EUR currencies (e.g. USD ↔ GBP), both currencies need a custom rate that month. If only one does, Light uses market rates for that whole conversion — see When Custom Rates Apply vs System Rates.

#Checking which rate was applied

Light records, for every conversion, whether your custom rate or the market rate was used. The exchange-rates report shows this per currency per day — check there (or ask support) to confirm your rates are being applied as expected.

#Related articles

• Setting a Custom FX Rate per Entity
• When Custom Rates Apply vs System Rates
• Currency Settings