domain-fintechfinancial-data-modeling

name	domain-fintech:financial-data-modeling
description	Guides financial data modeling: account structures (asset, liability, equity, revenue, expense), currency handling (ISO 4217, minor units), decimal precision (BigDecimal, integer cents), multi-currency ledgers, financial instrument representation, and temporal data patterns. Use when designing database schemas for financial applications.

Financial Data Modeling

When to use

• Designing database schemas for accounting or banking applications
• Choosing the right numeric type for monetary storage
• Modeling multi-currency accounts with FX gain/loss tracking
• Representing financial instruments (bonds, equities, derivatives)
• Implementing point-in-time queries and bi-temporal history
• Enforcing data integrity rules for financial records

Core principles

1. Never float money — use DECIMAL(19,4) or integer minor units; floating point errors compound
2. Currency is always explicit — every amount must carry its ISO 4217 currency code
3. Soft-delete only — status flags and effective dates, never DELETE financial records
4. Bi-temporal when auditability demands it — system time tracks inserts, business time tracks validity
5. Cost basis per lot — position tracking must support FIFO/LIFO/weighted average for tax reporting

Reference Files

• references/account-structures-currency.md — chart of accounts hierarchy, account model design, ISO 4217 compliance, floating-point avoidance, rounding rules per jurisdiction
• references/multi-currency-instruments.md — exchange rate management, multi-currency schema, realized vs unrealized FX gains, financial instrument hierarchy, position tracking
• references/temporal-data-integrity.md — effective dating, as-of queries, bi-temporal schema pattern, and data integrity constraints for financial tables