Choose a home currency
Use the currency in which you make most planning decisions or pay most obligations. A home currency is a reporting lens, not a claim that every account is denominated in it.
Keep original amounts
Store the amount and currency of each transaction or account. This preserves the source record and lets you revisit a conversion later without changing the historical purchase.
Choose a rate policy
You might use the actual card rate, a daily market estimate, a monthly planning rate or a manual fixed rate. Apply the policy consistently and label converted totals as estimates. Bank fees and spreads can make settlement amounts different.
Plan currency-specific obligations
Rent, cards or subscriptions due in another currency create exchange-rate risk. Keep enough of the required currency or include a margin rather than relying on today's converted balance.
Review gains and losses separately from spending
A home-currency total may change even when no transaction occurs. Distinguish exchange-rate movement from actual income or expense so reports remain understandable.
How Stash helps
Stash records transaction currencies, supports a home-currency view and allows manual rates or optional consent-based online rate refresh. Converted amounts are intended for personal budgeting, not official settlement.