Money across currencies.
WHY IT MATTERS HERE
Revenue and costs frequently span local and foreign currency, and rates move considerably.
WHAT TO STORE FOR EVERY TRANSACTION
The original amount The original currency The rate applied The converted amount The date the rate applies to
WHY STORE ALL OF THEM
So figures can be reproduced and explained.
WHAT NEVER TO DO
Store only a converted amount.
WHY
The conversion cannot be checked, corrected, or restated at a different rate.
WHAT RATE TO USE
Depends on the purpose: transaction-date rate for recording, period-average for reporting, closing rate for balances.
WHAT TO AGREE WITH FINANCE
Which applies where.
WHAT A RATES TABLE SHOULD HOLD
Rate, currency pair, date, and source.
WHAT TO HANDLE
Dates with no rate: weekends and holidays.
WHAT TO DO
Carry the last available rate forward, and record that you did.
WHAT TO BE CAREFUL WITH
Rounding, which accumulates across many rows.
WHAT TO ROUND
At presentation, not during calculation.
WHAT TO RECONCILE AGAINST
The finance system's own figures.
