Help Center / Organization Setup

Setting a Custom FX Rate for Your Company

By default, Light converts foreign-currency amounts using daily market rates, sourced automatically. If your business reports on fixed monthly FX rates — for example, a rate negotiated with your bank — you can have Light use your rate instead, so your books, payments, and month-end revaluation match your bank rather than the market.

What a custom rate does

A custom rate pins the conversion rate for one currency, for one month. It can be set for your whole company or scoped to a single entity — if both exist for the same currency and month, the entity-level rate takes priority. 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 to.
  • Scope — whether the rate should apply across your whole company, or just one entity.

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.
  • Month-scoped. A rate applies to transactions dated in its month only — it doesn't carry forward to later months, so set a rate for each month you want covered. 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 keeps track of which rate was applied to each transaction, including cases where a conversion fell back to the market rate. There's no self-serve screen for viewing this yet — if you want to confirm a specific conversion used your custom rate rather than the market rate, ask Light support and they can check for you.

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