A multi-currency cleanup, where some of the damage cannot be undone.

No. Intuit is explicit that once multicurrency is turned on in QuickBooks Online it cannot be turned off, because the currency conversion information has to keep being accounted for. Your home currency is also set at that moment and cannot be changed afterwards. That is why a multi-currency cleanup is partly a rebuild and partly a set of workarounds — some of what went wrong is permanent.

A realized gain or loss happens when a foreign transaction actually settles at a rate different from the one it was booked at — the money moved and the difference is fixed. An unrealized gain or loss is a paper movement on balances that are still open, recognized when those balances are revalued at a current rate. Both are legitimate; a file that records only one of them, or mixes them into a single account, cannot show either.

Through a home currency adjustment, which recalculates the home-currency value of a foreign balance at a newer rate and posts a journal entry for the difference. Intuit notes that the adjustment affects accounts receivable and accounts payable as unrealized gains or losses, and bank accounts as realized foreign exchange gains or losses — so which account is being revalued decides which kind of gain appears.

Usually because revaluation has not been run, has been run inconsistently, or has been run twice. A foreign balance carries two numbers — the amount in its own currency, which is what the counterparty agrees, and the home-currency value, which moves every time rates do. When only the first is being maintained, the balance sheet drifts silently while the counterparty statement still agrees, which is why nobody notices for months.

Not once transactions have been recorded against them. Intuit states that after a customer or supplier has recorded transactions you cannot change the currency in their profile, and one profile cannot hold more than one currency. The practical route is a second profile for the same real-world counterparty in the correct currency, which is workable but has to be done deliberately so the two are not later mistaken for duplicates.

Because currency has to line up across the entry. A payable belongs to an accounts payable account in the vendor's own currency, and QuickBooks will reject an entry where the vendor's currency and the account's currency disagree. That constraint is a common surprise during a cleanup, and it is also useful — it is one of the few places the software actively stops a mistake instead of recording it.

One per account per day. Intuit states that only one exchange rate can be saved per day per account, and that this rate is what unrealized gains and losses are calculated from. Files that trade at several rates in a day cannot capture each of them in the revaluation, so the difference lands as a realized amount at settlement instead — which is correct, but worth understanding before someone tries to make the two agree.

No. How foreign exchange gain and loss is treated on a return, and what documentation supports it, is a matter for your CPA and depends on your entity and where you operate. What we do is record the movements accurately and separately, so the person making that determination is working from figures they can rely on rather than reconstructing a year of currency movement.

Often not, and we will say so. A business with a handful of foreign purchases a year is usually better served by recording each at the rate it settled at and leaving revaluation alone. This cleanup earns its fee when foreign balances stay open across period ends, when several currencies are in play, or when the file has been running for a year or more without anyone maintaining the home-currency side.

A file where realized and unrealized movements sit in their own accounts, foreign balances carry a defensible home-currency value, currency assignments have been audited and any duplicate-profile workarounds documented, and a written record of every adjustment made. Where something could not be corrected because the setting is permanent, you get that in writing too rather than discovering it later.

No. Intuit says that once multicurrency is on, it can't be turned off, because the currency conversion records have to be kept from then on — and the home currency can no longer be changed. Downgrading to a plan without multicurrency means a new company file and a migration; we can do that, and reconcile the result.