What is a journal entry?

A journal entry is a record of a business transaction in the accounting system, showing which accounts are debited and credited and by what amounts. For professional service firms, journal entries record everything from client invoices (debit AR, credit Revenue) to payroll (debit Salary Expense, credit Cash) to equipment purchases (debit Equipment, credit Cash). Every transaction affects at least two accounts under the double-entry bookkeeping principle. Journal entries can be simple (two accounts) or compound (multiple accounts), but debits must always equal credits.

Key characteristics of a journal entry

1. Double-entry system: Every entry has equal debits and credits

2. Components: Date, accounts affected, debit amounts, credit amounts, description

3. Types: Standard entries (routine transactions), adjusting entries (accruals, deferrals), closing entries (year-end)

4. Reversing entries: Optional entries that reverse accruals in the following period

5. Supporting documentation: Receipts, invoices, and contracts substantiate entries

Why journal entry matters for service firms

Journal entries are the building blocks of financial statements. Every number on the P&L and balance sheet traces back to journal entries. Accurate entries ensure reliable reports; errors cascade through financial statements and tax returns. A consulting firm recognizing $50,000 in revenue in the wrong month distorts the monthly performance measurement. Adjusting entries enable accrual accounting: recording expenses when incurred (not when paid) and revenue when earned (not when received). Understanding journal entry logic helps business owners verify the bookkeeper's work and spot errors.

Example: Common journal entries for a consulting firm

Entry 1: Invoice the client for the completed project

1. Date: March 15

2. Debit: Accounts Receivable $45,000

3. Credit: Consulting Revenue $45,000

4. Description: Project Alpha final invoice

Entry 2: Record bi-weekly payroll

1. Date: March 20

2. Debit: Salary Expense $82,000

3. Debit: Payroll Tax Expense $12,730

4. Credit: Cash $66,450 (net pay)

5. Credit: Payroll Tax Payable $12,730

6. Credit: 401 (k) Withholding Payable $6,250

7. Credit: Health Insurance Payable $9,300

8. Description: Payroll period ending 3/15

Entry 3: Pay contractor

1. Date: March 22

2. Debit: Contractor Expense $8,500

3. Credit: Cash $8,500

4. Description: Payment to consultant for Project Beta

Entry 4: Adjusting entry for unbilled revenue

1. Date: March 31

2. Debit: Accounts Receivable $28,000

3. Credit: Consulting Revenue $28,000

4. Description: Accrue revenue for work completed but not invoiced

Entry 5: Record monthly depreciation

1. Date: March 31

2. Debit: Depreciation Expense $2,100

3. Credit: Accumulated Depreciation $2,100

4. Description: Monthly depreciation on office equipment