Learn systematic debit/credit rules for assets, liabilities, equity, revenue, and expense accounts
Systematic Debit & Credit Rules
Now that Sarah's seen the T-account structure, let's learn the systematic rules that determine which side of the T-account every transaction belongs on. These rules have been used by accountants worldwide for centuries.
Forget everything you think you know about "debit cards" and "credit cards." In accounting, these terms have very specific, simple meanings:
DEBIT (Dr.)
An entry made on the LEFT side of a T-account
From Latin "debere" meaning "to owe"
CREDIT (Cr.)
An entry made on the RIGHT side of a T-account
From Latin "credere" meaning "to trust"
That's it! Debit means left, credit means right. The confusion comes from knowingwhen to use the left side versus the right side for different types of accounts.
Professional accountants use the DEA LER acronym to remember which accounts increase with debits versus credits:
DEA
Increase with DEBITS (Left Side)
- Dividends - Money paid to owners
- Expenses - Costs of running the business
- Assets - Things the business owns
Sarah's Example: When cash increases, debit Cash. When she pays rent, debit Rent Expense.
LER
Increase with CREDITS (Right Side)
- Liabilities - Debts the business owes
- Equity - Owner's stake in the business
- Revenue - Money earned from customers
Sarah's Example: When she earns revenue, credit Revenue. When she takes a loan, credit Notes Payable.
Memory Tip: Think "DEAlers drive on the LEFT, LERners stay RIGHT." Once you memorize DEA LER, you'll never forget which accounts increase with debits versus credits!
Here's the unbreakable rule that makes Sarah's self-auditing ledger possible:In every single transaction, total debits must equal total credits.
This isn't just a suggestion—it's the fundamental law of double-entry bookkeeping. When Sarah follows this rule correctly, her books will automatically stay balanced, and she'll be able to catch any errors immediately.
Sarah's $650 Pet Grooming Payment Example:
Step 1: Identify what increased
• Cash (an Asset) increased by $650
• Revenue increased by $650
Step 2: Apply DEA LER rules
• Debit Cash $650 (Asset increases with debit)
• Credit Revenue $650 (Revenue increases with credit)
âś… Perfect Balance: $650 debits = $650 credits
These systematic debit and credit rules aren't just academic exercises—they're the foundation of financial credibility. When Sarah can demonstrate that she follows these universal accounting standards, potential investors immediately understand that her financial information is reliable and comparable to any other business. More importantly, these rules will allow her to build Excel formulas that automatically verify her work, creating the self-auditing system that distinguishes professional bookkeeping from amateur record-keeping.