Amounts and directions

amount is always positive. direction carries the sign. To get a signed figure, negate when direction is debit.

How direction is decided#

From the document, never from the payee name. Issuers encode it four ways:

1. A sign on the amount. A leading or trailing minus, or brackets.
2. A section heading that owns every row beneath it, such as CHECKS AND OTHER DEBITS. The rows themselves carry no marker.
3. Paired columns, Débit | Crédit, where the column decides the direction.
4. A marker against a default. On a card statement every row is a charge unless it carries CR.

Income#

Only count credits on type: "bank" accounts. A credit card's credits are the monthly repayment and merchant refunds. Summing credits across every account in a file inflates income by whatever the customer spent on the card.

const income = doc.accounts
  .filter((a) => a.type === "bank")
  .reduce((sum, a) => sum + a.totals.credits, 0);

The same applies in reverse. A payment from a current account to a credit card is not spending if you also hold that card's statement for the month, because the purchases it settles are itemised there.

Totals#

A gap between the two is usually a difference of convention. See Verification.