Design and implement a daily interest and fee accrual ledger for a BaaS deposit product using double-entry journal entries

Steps

1. Define the ledger account structure: for each customer deposit account create at minimum an asset account (customer deposit balance), an interest payable liability account (accrued but not yet credited interest), and an interest expense account; for fee-bearing products also create a fee receivable asset account and fee income revenue account
2. Implement a daily end-of-day accrual job: for each account calculate the day's interest accrual as (current balance * annual rate / 365); create a double-entry ledger transaction that debits the interest expense account and credits the interest payable liability account for the calculated accrual amount
3. At the interest posting date (typically monthly or per product terms), create a second journal entry that debits the interest payable liability and credits the customer deposit balance account, increasing the customer's principal balance by the accrued interest amount — this is the interest capitalization event
4. For fee accrual, follow the same pattern: daily accrual debits an accrued fee receivable and credits fee income; on the fee charge date create an entry debiting the customer deposit balance and crediting the accrued fee receivable to net out the accrual and record the actual deduction from principal
5. Ensure all accrual entries carry the accrual date (the economic date of the accrual) rather than the posting timestamp in the ledger transaction effective date field, so month-end trial balance calculations are correct even if the batch job runs past midnight
6. Implement a reconciliation check after each accrual run: the sum of all interest payable liability balances should equal the total accrued-but-uncredited interest outstanding across all accounts; drift in this check indicates a missed accrual or an incorrect posting that needs correction