Journal entry accounting is the practice of recording each business transaction in a dated log that names the accounts affected and shows equal amounts on the debit and credit sides. Every financial statement, tax return, and audit trail traces back to these entries, so the mechanics matter. Federal law requires businesses to keep records that clearly establish income, deductions, and credits,1Office of the Law Revision Counsel. 26 USC 6001 Notice or Regulations Requiring Records, Statements, and Special Returns and those records begin at the journal.
The whole system rests on one equation: assets equal liabilities plus equity. Every entry must keep that equation in balance, which means every transaction touches at least two accounts, with one account debited and another credited for the same dollar amount. Buy $500 in office supplies with cash and supplies goes up by $500 (debit) while cash goes down by $500 (credit). This is double-entry accounting, and it has been the standard for centuries because it catches mistakes single-entry bookkeeping cannot. If debits and credits don’t match at period end, something went wrong.
Debit and Credit Rules by Account Type
The hardest part of journal entries for most people is remembering which accounts increase with debits and which increase with credits. The rules follow the logic of the accounting equation:
- Assets: debits increase, credits decrease. Cash, equipment, inventory, and accounts receivable all follow this pattern.
- Liabilities: credits increase, debits decrease. Loans payable, accounts payable, and accrued expenses work this way.
- Equity: credits increase, debits decrease. Owner’s equity and retained earnings sit on the same side of the equation as liabilities.
- Revenue: credits increase. Revenue feeds into equity, so recording a sale means crediting the revenue account.
- Expenses: debits increase. Expenses reduce equity, so recording rent or payroll means debiting the expense account.
“Normal balance” refers to whichever side increases the account. Assets and expenses have normal debit balances. Liabilities, equity, and revenue have normal credit balances. An account sitting on the wrong side of its normal balance is a red flag worth investigating.
What a Journal Entry Contains
Before you record anything, you need a source document. That might be a bank statement, a vendor invoice, a sales receipt, or a payroll report. The IRS expects businesses to keep documents supporting the entries in their books and on their tax returns, so the source document is not optional paperwork. It is the evidence that justifies the entry if anyone questions it later.
Each entry contains the same core elements:
- The date of the transaction, which sets its place in the chronological sequence.
- The specific account names, pulled from the company’s chart of accounts. The chart is the master list of accounts, organized into assets, liabilities, equity, revenue, and expenses, with each account typically assigned a numerical code whose first digit identifies the category.
- The dollar amounts in the debit and credit columns.
- A brief description or memo explaining the business purpose. This seems like busywork until months later, when you are trying to figure out why a particular entry exists.
- A reference number, such as an invoice ID or check number, so the entry can be traced back to its source document.
Accounting software handles much of this structure automatically through drop-down account selection, auto-populated dates, and validation checks that block entries where debits and credits don’t match. The automation helps, but it does not replace understanding what the software is doing behind the interface.
Compound Entries With Three or More Accounts
Not every transaction fits neatly into two accounts. When a single event affects three or more, you record it as a compound journal entry. If a customer pays a $1,000 invoice but takes a $50 early-payment discount, the entry hits three accounts: cash goes up by $950 (debit), the sales discount account goes up by $50 (debit), and accounts receivable goes down by $1,000 (credit).
The rule does not change. Total debits still equal total credits. In the example above, $950 plus $50 equals $1,000. Whether an entry involves two accounts or twelve, the equation must balance. Compound entries are common in payroll, in loan payments that split between principal and interest, and in sales transactions involving tax or discounts.
Posting to the General Ledger
Recording the journal entry is only half the process. The entry still needs to move from the journal into the general ledger, which organizes transactions by individual account rather than by date. This transfer is called posting. In the ledger you can see every transaction that affected a single account over time, which is far more useful for analysis than the chronological journal view.
Modern software posts automatically when you save or approve an entry. The system assigns a unique transaction ID, updates account balances in the ledger, and refreshes the trial balance in real time. The trial balance is a list of every account and its current balance, arranged to show total debits on one side and total credits on the other. If those totals do not match, the software will usually flag the problem or block the entry.
In manual systems, posting means writing the debit and credit amounts into the correct ledger pages and cross-referencing the journal entry number. Slower, but the logic is identical.
Fixing an Unbalanced Trial Balance
When total debits and credits on the trial balance don’t match, the error almost always traces back to a small set of common mistakes:
- One-sided entries, where only the debit or only the credit was recorded.
- Double-sided errors, where both sides were posted as debits or both as credits.
- Mismatched amounts, where the debit and credit were recorded for different dollar values.
- Calculation errors, where the individual entries were correct but the running account balance was added up wrong.
- Transfer errors, where an account balance was correct in the ledger but copied to the trial balance incorrectly.
- Omitted accounts, where an account with a balance was left off the trial balance entirely.
Two arithmetic tricks help. If the trial balance is off by an even number, divide the difference by two and search entries for that amount; a posting on the wrong side creates a discrepancy of exactly double the transaction amount. If the difference is divisible by nine, you likely have a transposition error, where two digits were swapped when entering a number.
Adjusting, Closing, and Reversing Entries
Standard operating entries capture normal business activity as it happens: recording a sale, paying a vendor, purchasing inventory, receiving a loan payment. They make up the bulk of most companies’ journal activity. Three other types run on the calendar rather than on transactions.
Adjusting Entries
At the end of each reporting period, adjusting entries bring the books into alignment with economic reality under accrual accounting. Accrual accounting recognizes revenue when earned and expenses when incurred, regardless of when cash changes hands, and that creates timing gaps that adjusting entries fix.
Accruals record revenue or expenses that have occurred but haven’t been invoiced or paid yet. If your company owes employees three days of wages at the end of December but won’t pay until January, an adjusting entry debits wage expense and credits wages payable so December’s financial statements reflect the true cost of that month.
Deferrals work in the opposite direction. If you paid a full year of insurance premiums in advance, only the portion used during the current period belongs on this period’s income statement. An adjusting entry moves the unused portion from the expense account into a prepaid asset account.
Closing Entries
Closing entries happen at the very end of the accounting cycle. They reset the temporary accounts, meaning revenue, expenses, and dividends, back to zero so the next period starts clean. The net result transfers into retained earnings on the balance sheet: if revenue exceeded expenses, retained earnings increases; if expenses were higher, it decreases. Without closing entries, revenue and expense accounts would accumulate across periods and make it impossible to measure any single period’s performance.
Reversing Entries
On the first day of a new period, some companies record reversing entries that undo the accrual adjustments made at the end of the prior period. This is not required, but it simplifies processing. When the actual invoice or payment arrives during the new period, the bookkeeper records it normally without having to manually account for the portion already accrued. Reversing entries reduce the chance of double-counting revenue or expenses during the transition.
How to Correct a Posted Entry
Mistakes happen, and accounting has clear rules for fixing them. You never erase or delete a posted journal entry. Instead, you record a new correcting entry that offsets the original error and applies the correct amounts. This preserves the audit trail by showing exactly what was wrong and how it was fixed.
If you accidentally debited office supplies for $300 when the charge should have gone to equipment, the correcting entry debits equipment for $300 and credits office supplies for $300. The original wrong entry stays in the journal. The correcting entry neutralizes it and puts the money where it belongs. Auditors and the IRS need to see the complete history of changes, not a sanitized version where errors have been quietly overwritten.
Records the IRS Expects You to Keep
The federal regulation implementing the record-keeping statute requires businesses to maintain permanent books of account or records, including inventories, sufficient to establish gross income and deductions.2eCFR. 26 CFR 1.6001-1 Records How long you keep those records depends on what they document. The IRS provides these general guidelines:3Internal Revenue Service. How Long Should I Keep Records
- Three years is the standard retention period for records supporting income, deductions, or credits on a tax return, measured from the filing date.
- Six years applies if you fail to report income exceeding 25% of the gross income shown on your return.
- Seven years applies if you claim a loss from worthless securities or a bad debt deduction.
- Four years applies to employment tax records, measured from the date the tax is due or paid, whichever is later.
- Indefinitely, if you don’t file a return or file a fraudulent one.
Property records deserve special attention. Keep records related to buildings, vehicles, or equipment until the statute of limitations expires for the year you dispose of the property. Those records establish your basis for calculating depreciation and any gain or loss on sale.
Penalties for Inadequate Records
The consequences for poor record-keeping go beyond failing an audit. If inadequate records lead to an underpayment of tax, the IRS can impose an accuracy-related penalty of 20% on the underpaid amount.4Office of the Law Revision Counsel. 26 USC 6662 Imposition of Accuracy-Related Penalty on Underpayments That penalty applies to underpayments caused by negligence or disregard of rules, substantial understatements of income tax, and similar issues that often trace back to sloppy or missing journal entries.
At the extreme end, willfully failing to keep required records is a federal misdemeanor. A conviction carries a fine of up to $25,000 for individuals or $100,000 for corporations, up to one year in prison, or both.5Office of the Law Revision Counsel. 26 USC 7203 Willful Failure to File Return, Supply Information, or Pay Tax The word “willfully” is doing a lot of work in that statute. Honest mistakes and disorganized filing cabinets don’t land anyone in prison. Deliberately destroying records or refusing to maintain books when you know the law requires them crosses into criminal territory.