# Differences between the core system and the ledger: where they come from *The points in the process where the two records diverge, and how to address them at close.* At a financial institution, the core system and the general ledger record the same transactions. The core records them as what they are: a disbursement, a payment, a renewal. The ledger records them as entries in accounts. In theory, at the end of each day both records say the same thing. In practice, many teams discover the differences at month-end close, when they are already costly to explain. This article describes where those differences come from and what can be done to find them during the month, not at the end. ## Two records, two logics The core works with contracts and events: each transaction has a customer, a product, a date and a status. The ledger works with accounts and balances: each entry moves amounts between accounts without necessarily keeping the detail of the contract that originated it. Between the two there is a translation: rules that turn events into entries. When that translation is complete, documented and runs the same way every day, the records match. Differences appear when any of those three conditions fails. ## Where the differences come from ### Events without an accounting rule The core adds a new product, a special condition or a type of transaction that did not exist when the rules were defined. The transactions are recorded in the core and generate no entry, or a generic one. This is the most frequent cause at institutions that grow fast or launch products often. **How to detect it:** a daily control of core events with no associated entry, or with an entry to a “bridge” account that should be zero at the end of the day. ### Incomplete or ambiguous rules The rule exists, but does not cover every case: a renewal with a rate change, a partial payment, a foreign currency transaction with an exchange rate from another date. The entry is generated, but for an amount different from the core’s. **How to detect it:** an operational-to-accounting reconciliation at contract level, not just totals. Totals can tie out by offsetting while individual contracts differ. ### Different cut-off dates The core closes the day at one time; the ledger takes its balances at another. Transactions that fall between the two cut-offs appear in one record and not the other, and are regularized the next day. It is not an error, but if it is not documented, every day produces a difference someone has to explain. **How to detect it:** document the cut-off time of each source and classify “cut-off” differences automatically so they do not consume review time. ### Manual adjustments A manual entry corrects a difference in the ledger without correcting the core, or the other way round. The difference disappears from today’s reconciliation and reappears tomorrow, because the cause is still there. **How to detect it:** record every manual adjustment with its cause and review periodically which ones repeat. An adjustment that repeats every month is a missing accounting rule. ## What changes when they are found during the month If differences are identified at close, the team explains them in a hurry, with the last day’s information and the calendar against it. If they are identified daily, each one has a visible cause and a small correction. What we have seen work: - **An automated daily reconciliation** between core and ledger, at the level of detail at which both can be compared, with differences classified by cause. - **One person in charge per type of difference**, who decides whether to correct the core, the ledger or the rule. - **An inventory of accounting rules** by product and event, reviewed every time the core changes. At institutions that have implemented Oracle Accounting Hub, that inventory of rules is the heart of the platform: every entry is explained from the event and the rule applied. But the principle holds with any system: differences originate in the translation between events and entries, and that is where to look. ## Where to start If the close drags on because of differences explained at the end, the first step is to classify the differences of the last few closes by cause. That classification usually shows that most of them concentrate in two or three products or in one type of event, and points to which rule, cut-off or adjustment to fix first. --- Fuente: https://savi.com.pe/en/articles/core-system-and-the-ledger/