Core banking
The ledger of the bank: accounts, balances and every posting against them.
01 What it holds
The data inside it
Customer accounts, product terms, interest accruals, transactions and the end-of-day positions everything else reconciles to.
Customer, Account, Product, Posting / Transaction, Balance, Interest accrual, Limit
02 Getting the data out
Extraction, and the keys that decide whether it joins
End-of-day batch extracts remain the norm, with CDC where the platform supports it. The daily cycle defines what "current" means for the whole bank.
Customer identifiers are per system and frequently per product line, so the same person holds a current account, a loan and a card under three identities.
03 What goes wrong
The failures that look like success
Each of these produces a number that is plausible, reconciles to something, and is wrong. They are worth reading before the first extract, not after the first dispute.
Customer versus account versus party
Most core systems are account-centric. Any relationship metric requires resolving accounts to a customer and customers to a household or group.
End-of-day defines the day
Intraday queries against a batch-oriented core produce figures that do not tie to any published balance.
Product configuration encodes the logic
Interest, fee and charge behaviour is configuration rather than data, and it changes without a data-model change.
Backdated and reversed postings
Value date and posting date differ, and reversals restate history. Both must be modelled or balances will not reconcile.
04 Joins that matter
What this system is worth joining to
| Join to | What it lets you answer |
|---|---|
| CRM | relationship view across products |
| Risk and finance | exposure to general ledger, staged consistently |
| Payments switch | transaction-level behaviour behind the balance |
05 Metrics it feeds
The numbers that come out of it
06 Questions
Frequently asked
Why is one customer view so hard in a bank?
Because the core is organised around accounts and products, often on several platforms after decades of acquisitions. Resolution is not a nice-to-have here: exposure, share of wallet and most regulatory obligations are all defined per customer or per group.
Can we report intraday from a batch core?
Only for what the core publishes intraday. Anything else has to be reconstructed from transaction streams, and the difference from the end-of-day position must be stated explicitly.
Connect this system without replacing it
SCIKIQ reads it in place, resolves the entities inside it and governs what the fields mean.