Posting to the General Ledger

Why the general ledger is where numbers become accountable

A manager reviewing January results asks a simple question: "How much cash do we actually have, how much do customers still owe us, and did payroll land in the right month?" Those answers do not live in a stack of invoices or in a single journal page. They live in the general ledger (GL), the master set of accounts that accumulates every debit and credit the company has recorded.

Through Unit 1, you built the conceptual foundation. Why Accounting Exists established why stakeholders demand verifiable records. In The Accounting Equation, you learned that A = L + E (assets equal liabilities plus equity) must hold at all times. In Unit 2, Double-Entry Bookkeeping showed why every event hits at least two accounts, Debits and Credits gave you the increase/decrease rules by account type, and Journal Entries taught you to document transactions in chronological form. Posting is the bridge step: it transfers amounts from the journal into individual GL accounts so each account shows its activity and its balance.

When posting is late, duplicated, or posted to the wrong period, the damage is not theoretical. A chief financial officer (CFO) can present a balanced trial balance while wage expense is double-counted. A lender reviewing internal reports can see receivables that do not tie to customer statements. An operator planning February hiring can trust a cash balance that includes uncleared items nobody reconciled. Posting discipline is how raw transactions become numbers a board, a bank, and a management team can defend.

This lesson teaches the mechanics and the managerial stakes: how posting works, how T-accounts relate to the formal ledger, how running balances are computed, how control accounts tie to subsidiary ledgers, how enterprise resource planning (ERP) systems post automatically, why period cutoffs matter, how bank reconciliation connects to the GL cash account, and how duplicate posting errors hide inside a system that still "balances."

The posting process: from journal entry to general ledger account

A journal is the company's chronological diary of accounting events. Each journal entry records a transaction's date, the accounts affected, debit amounts, credit amounts, and a brief memo. The journal answers: "What happened, in what order?" The GL answers: "What is the total balance in each account after all those events?"

Posting is the act of copying each debit and credit from journal entries into the correct GL accounts. If January includes forty journal entries that touch Cash, posting adds each Cash debit and each Cash credit to the Cash account in the GL. After posting, Cash shows total debits, total credits, and a net balance (the amount that will appear on reports).

The classic manual sequence looks like this:

1. Record the transaction in the journal (or approve it in software).
2. Post each line of the entry to the relevant GL account.
3. Compute a running balance for each account.
4. List all account balances in a trial balance (a two-column list that checks whether total debits equal total credits).

In modern companies, steps 2 and 3 often happen instantly when a clerk approves an invoice or when payroll is finalized. The logic is unchanged. The GL is still the roll-up layer between detailed entries and financial statements.

A useful mental picture: the journal is a time-ordered film reel; the GL is the season summary statistics for each character. You need both. Auditors trace from financial statement line → GL balance → journal entry → source document (invoice, contract, bank statement). If posting is wrong, that trail breaks even when totals still foot.

Managers rarely post entries themselves in mid-size and large firms, but they consume GL outputs constantly: departmental profit and loss (P&L) (income statement) reports, aged receivables, cash forecasts, and board packages. When a GL balance looks "off," the first investigative question is not "Was the strategy wrong?" but "Did we post correctly, completely, and in the right period?"

T-accounts versus the formal general ledger

A T-account is a teaching scaffold shaped like the letter T. Debits go on the left; credits go on the right. The horizontal bar is the account name (Cash, Accounts Payable, Service Revenue). T-accounts help you see how a single account breathes: infows on one side, outflows on the other, net position at the bottom.

The formal general ledger is the production version of the same idea. Instead of pencil on paper, the GL is a structured table (in software or historically in a bound book) with one row per account and columns for date, reference, debit, credit, and running balance. Large ERP systems store millions of lines; the GL account summary screen is what accountants use at month-end.

T-accounts and the GL are not competing systems. They are the same logic at different scale:

In Journal Entries, you posted March transactions to T-accounts and verified that assets, liabilities, and equity still satisfied A = L + E. That exercise was posting in miniature. The only difference in practice is scale and controls: ERP systems enforce account numbers from the COA, block unbalanced entries, and attach electronic approvals.

Beginners sometimes believe T-accounts are "for students" and the GL is "real accounting." Both are real. Public company controllers still sketch T-accounts on whiteboards when debugging a messy quarter. The GL is where those sketches must ultimately reconcile.

When you read an internal report showing "Cash: $1.2 million," that number is the GL Cash account balance after posting, not the bank balance and not a single journal line. The gap between GL Cash and the bank balance is exactly why companies perform bank reconciliation (covered later in this lesson).

Running balances: how accountants know where an account stands

After each posting, accountants update a running balance: the net debit or credit position of the account at that point in time. For accounts with a normal debit balance (most assets and expenses), running balance equals cumulative debits minus cumulative credits. For accounts with a normal credit balance (most liabilities, equity, and revenue), running balance equals cumulative credits minus cumulative debits.

Consider Cash, an asset with a normal debit balance. If Cash starts January at $25,000 debit and the next event credits Cash for $4,500, the running balance falls to $20,500 debit. If a later debit adds $10,000, the balance rises to $30,500 debit. Each line in the Cash ledger should show the transaction and the balance after it posts.

Running balances matter for three practical reasons:

Speed at month-end. The trial balance pulls ending running balances from every account. Without running balances, accountants would re-add every historical line each time they need a report.

Error detection during the month. If Cash shows a credit running balance, something unusual happened: perhaps a data import duplicated credits, or a refund was coded incorrectly. Good teams investigate before the problem compounds.

Operational decisions before the month closes. A credit manager checking Accounts Receivable (AR, amounts customers owe the company) should see current GL balances, not last month's statement. Posting lag can hide a collections problem until it is too late.

The running balance is not a separate truth from debits and credits. It is a convenience calculation. The economic story still comes from understanding which transactions hit the account and why.

From Debits and Credits, remember that revenue accounts increase with credits. A Service Revenue running credit balance of $37,000 means the company recorded $37,000 of earned revenue in the period (before adjustments). Expense accounts increase with debits. Wage and rent expense balances will reduce net income on the P&L when the period is summarized.

Control accounts and subsidiary ledgers

Some GL accounts summarize large populations of detail. Accounts receivable (AR) might total $4.2 million on the balance sheet, but that balance is the sum of hundreds of customer invoices. Accounts payable (AP) (amounts the company owes suppliers) might total $1.8 million, composed of individual vendor bills.

A control account is a GL account that holds the official, consolidated balance presented on financial statements. A subsidiary ledger (also called a subledger) holds the supporting detail by customer, vendor, employee, or fixed asset. The subsidiary ledger is part of the accounting system, but it is not the GL itself. It feeds the control account.

The cardinal rule: the sum of subsidiary ledger balances must equal the control account balance in the GL. If AR control shows $420,000 but customer subledger lines sum to $415,000, you have a $5,000 reconciliation gap. That gap might be a posting error, a timing difference between modules, or a data extract mistake. It is never something to ignore because the trial balance still balances.

Why maintain two layers? Efficiency and responsibility. The GL stays clean enough to map directly to statement lines. Sales teams or collection specialists can work customer detail without editing GL structure. Auditors can test control account totals to financial statements, then drill into subsidiary samples.

Common control accounts and their typical subledgers:

Managers use subsidiary data for operations (who is past due?) and GL control data for covenant compliance (total AR within borrowing base limits?). When the two do not tie, both uses are unsafe.

Posting in enterprise resource planning systems

An enterprise resource planning (ERP) system is integrated software that connects accounting with operations: sales orders, inventory, payroll, purchasing, and more. When a warehouse ships goods to a customer, the ERP can automatically create and post: debit AR, credit Sales Revenue, debit COGS (cost of goods sold, the inventory cost of what was sold), credit Inventory. The manager approving the shipment may never see the journal entry, but the GL updates immediately upon approval.

ERP posting workflows usually include:

Master data controls. The COA is configured once. Clerks pick valid account combinations; the system rejects nonsense pairings.

Approval chains. A $250,000 vendor invoice might require department head and CFO approval before it posts to GL.

Batch jobs. Payroll, depreciation, and allocation entries often post as reviewed batches with audit logs.

Reversal and adjustment tools. Errors are corrected with reversing entries rather than silent deletes (deletes destroy audit trails).

For leaders, the managerial shift is from "posting accuracy depends on one accountant's spreadsheet" to "posting accuracy depends on process design." Weaknesses move to: duplicate batch runs, incorrect default GL accounts on vendor records, and interfaces that import sales from a website at midnight with wrong tax mappings.

A healthy month-end includes exception reports: unposted documents, entries by unusual users, accounts with negative balances where policy forbids them, and round-dollar manual journals over a materiality threshold. Posting in ERP is fast; detective work is still human.

Period cutoffs: posting in the correct accounting period

GAAP (Generally Accepted Accounting Principles, the primary U.S. accounting rulebook) and sound management both require that transactions be recorded in the period when the economic event occurs, not merely when someone types them into software. Cutoff is the discipline of drawing that line at month-end or year-end.

A classic failure: a company ships $2 million of product to a distributor on December 28, but the warehouse clerk does not mark the shipment "complete" in ERP until January 3. If revenue posts only upon system completion, January revenue is overstated and December is understated. Lenders and investors comparing quarters see a distorted trend.

Cutoff testing is standard audit work. Auditors select late-December and early-January entries and inspect shipping documents, service completion memos, or signed contracts to see whether GL posting matches economic timing. Managers should expect questions like: "Show me December revenue entries above $50,000 and their proof of delivery date."

Practical cutoff controls include:

Hard close dates. After February 3, January GL is locked except for controlled adjusting entries.

Shipping terms discipline. FOB (free on board) shipping point versus destination determines when title transfers; operations and accounting must agree.

Accrual templates. Wages earned December 29–31 but paid January 5 still require a December wage expense accrual (you will formalize accruals in Unit 3).

Checklists. AR cutoff: were all December shipments invoiced? AP cutoff: were all December goods received recorded?

Posting to the wrong period does not automatically break the trial balance. That is what makes cutoff errors insidious. Totals still foot; the story is wrong.

Bank reconciliation and the GL cash account

Cash in the GL is the company's record of cash movements based on accounting entries. The bank statement is the bank's record of the same account. They should reconcile, but they will not match line-for-line every day because of timing differences.

Common reconciling items:

Bank reconciliation is the monthly (or daily) procedure that explains differences and confirms the GL Cash balance is supportable. The adjusted bank balance should equal the adjusted book (GL) balance when complete.

Reconciliation protects against fraud and posting errors. If payroll duplicated a credit to Cash but the bank withdrew funds only once, the GL Cash balance will be lower than reality after adjusting for timing items. An unexplained reconciling item is a stop sign.

Operators sometimes say "we have plenty of cash" based on a banking app. Finance teams answer with GL Cash plus reconciliation status: "We have $X per books, $Y per bank, difference fully explained except $Z under investigation." That discipline prevents spending cash already committed by uncashed checks.

Duplicate posting and other GL integrity failures

Because double-entry bookkeeping always pairs debits and credits, a balanced trial balance can still hide serious errors. Duplicate posting is a frequent real-world example: the same approved payroll batch or vendor payment file runs twice.

Suppose payroll should post:

If the batch runs twice:

Debits still equal credits. Wages Expense is doubled, so net income (NI) (revenue minus expenses for the period) is understated by $48,000. GL Cash is understated by $48,000 relative to a single payment. The bank, however, withdrew cash only once. Bank reconciliation therefore shows a large unexplained difference unless someone ties it to duplicate system posting.

Other integrity failures that survive a balanced trial balance:

Posting to the wrong account. A $12,000 collections receipt debits Cash correctly but credits Sales Revenue instead of AR. Cash is right; AR is overstated; revenue is overstated.

Omission. A shipment never invoiced: no journal, no GL update, trial balance unchanged, revenue missing.

Compensating errors. Two mistakes that accidentally offset in the trial balance totals but distort individual accounts.

Wrong period posting. January rent expensed in February: balances foot, January margin wrong.

Detection tools beyond the trial balance include: subsidiary ledger tie-outs, bank reconciliation, budget-to-actual variance analysis, and ratio spikes (wages as percent of revenue jumps with no headcount change).

Harborline Consulting LLC provides project management services to mid-size manufacturers. The CFO wants January GL balances to support a lender covenant review on February 5. Your job in this example is to journalize (already done below), post to T-accounts, compute running balances, prove A = L + E, and preview the unadjusted trial balance that Lesson 5 will formalize.

Part A: Opening balances and January journal entries

Opening balances at January 1, 2026:

Opening equation check: Assets = 25,000 + 8,000 + 2,000 + 40,000 = $75,000. Liabilities + Equity = 6,000 + 65,000 + 4,000 = $75,000. 75,000 = 75,000 ✓

January journal entries (from approved source documents):

Each entry balances debits and credits individually. Posting will accumulate these amounts into each GL account.

Part B: Posting to T-accounts with running balances

Cash (normal debit balance):

Accounts Receivable:

Supplies:

Equipment: No January activity. Ending balance $40,000 Dr.

Accounts Payable (normal credit balance):

Common Stock:

Retained Earnings: No direct January entries. Ending balance $4,000 Cr (unchanged until closing entries in a later unit).

Service Revenue (normal credit balance):

Rent Expense: JE3 → $4,500 Dr. Salaries Expense: JE8 → $12,000 Dr.

Posting is complete when every journal line has been copied into its account and running balances are updated.

Part C: Reconciliation to the accounting equation and trial balance preview

January net income (not yet closed to RE):

Service Revenue 37,000 − Rent Expense 4,500 − Salaries Expense 12,000 = $20,500

Ending balance sheet elements (unadjusted, before Unit 3 adjustments):

Equation check: 103,700 = 4,200 + 99,500 = 103,700 ✓

Unadjusted trial balance preview (feeds Lesson 5):

120,200 = 120,200 ✓ The trial balance balances because every journal entry balanced and posting preserved equality.

Part D: Managerial read

The lender's covenant includes a minimum tangible net worth test. Harborline's equity rose from $69,000 at January 1 (65,000 stock + 4,000 RE) to $99,500 economically (including January profit), while cash fell from $25,000 to $25,500 despite $20,500 of profit because collections lagged billing and the owner investment offset operating cash uses. A manager who looks only at Cash might think January was flat. A manager who reads posted GL balances sees profitable operations with working capital tied in AR.

Before signing the covenant certificate, the CFO should confirm: AR subsidiary ties to the $35,000 control balance, January 20 billing to Brookfield is not a cutoff error, and the unadjusted trial balance will be the starting point for Lesson 5's mechanical check before accrual adjustments in Unit 3.

Summit Retail Co. sells outdoor equipment through wholesale contracts. January month-end work involves three detective tasks: prove AR subsidiary equals GL control, reconcile GL Cash to the bank statement, and explain why wage expense looks too high even though the trial balance balances.

Part A: AR control account and customer subsidiary ledger

GL AR control balance, January 1: $42,000

Customer subsidiary ledger, January 1:

42,000 = 42,000 ✓ at opening.

January AR activity (same amounts posted to both subsidiary and control):

Ending subsidiary balances:

GL AR control ending balance: 42,000 + 12,000 − 8,000 + 6,500 − 10,000 = $42,500

42,500 = 42,500 ✓ Subledger ties to control. If collections clerk posted Jan 12 cash to Brookfield in the subledger but the journal entry accidentally credited AR control without subledger update, the gap would flag a posting defect before financial statements.

Part B: Bank reconciliation exposes duplicate payroll before month-end close

GL Cash before payroll postings, January 31: $110,400 (all non-payroll January activity already posted).

Correct January 31 payroll entry (single ACH, automated clearing house, withdrawal):

After one correct posting, GL Cash should be: 110,400 − 48,000 = $62,400.

Processing error: payroll batch PR-2026-01 ran twice in ERP. The duplicate posted the same entry a second time:

GL balances after duplicate (erroneous):

Cash proof: 110,400 − 48,000 − 48,000 = 14,400 Dr ✓

The bank, however, processed only one $48,000 ACH withdrawal. Bank statement balance, January 31: $58,900.

Bank reconciliation workpaper (January 31):

62,400 − 14,400 = 48,000 ✓ The difference equals exactly one payroll credit. That is not a timing item; it is a duplicate posting fingerprint.

Until reconciling items are documented, a manager should not treat $58,900 (raw bank) or $14,400 (erroneous GL) as actionable cash.

Part C: Correcting the duplicate and restoring GL integrity

Reversing entry (February 1) to undo the duplicate batch:

After reversal:

Reconciliation after correction:

Trial balance note: Even before the reversal, total debits equaled total credits because both payroll postings were balanced pairs. The system looked arithmetically fine while economically wrong: wage expense and GL Cash were both misstated by $48,000 in opposite directions. Bank reconciliation supplied the external proof the trial balance could not.

Part D: Managerial read

Summit's board asks why January wages are 22% of revenue versus 18% budget. The answer is not "labor market inflation" but "duplicate payroll batch PR-2026-01." Without subledger and bank reconciliation discipline, the wage spike might be debated for hours.

The AR tie-out proves billing integrity at the customer level. The bank reconciliation proves cash defensibility. Together they show why Lesson 5's unadjusted trial balance is only a first checkpoint: it confirms double-entry math, not operational truth.

Ridgeway Media Inc. begins February with the following posted GL balances:

February journal entries:

1. Feb 4: Provided services $9,000 on credit.
2. Feb 9: Collected $6,500 from customers on account.
3. Feb 14: Paid $2,800 cash for February utilities.
4. Feb 18: Purchased equipment $15,000; paid $5,000 cash and signed a note for the remainder.
5. Feb 25: Paid $4,000 on accounts payable.

Tasks:

1. Post the five entries to T-accounts for Cash, AR, Equipment, AP, Utilities Expense, Service Revenue, and Notes Payable.
2. Compute ending running balances.
3. Verify A = L + E including February net income in equity.
4. Prepare an unadjusted trial balance and confirm it balances.

Solution

Entry summaries:

Cash running balance:

18,000 + 6,500 − 2,800 − 5,000 − 4,000 = $12,700 Dr

AR: 11,000 + 9,000 − 6,500 = $13,500 Dr

Equipment: 30,000 + 15,000 = $45,000 Dr

AP: 7,000 − 4,000 = $3,000 Cr

Notes Payable: $10,000 Cr (new)

Service Revenue: $9,000 Cr

Utilities Expense: $2,800 Dr

February net income: 9,000 − 2,800 = $6,200

Assets: 12,700 + 13,500 + 45,000 = 71,200

Liabilities: 3,000 + 10,000 = 13,000

Equity: 40,000 + 12,000 + 6,200 NI = 58,200

Check: 71,200 = 13,000 + 58,200 = 71,200 ✓

Unadjusted trial balance:

Explain why: Entry 4 increases assets (Equipment) by $15,000 and increases liabilities (Notes Payable $10,000) and decreases Cash $5,000. Equity is unchanged at the moment of purchase because no revenue or expense is recorded. The trial balance balances because each entry preserved equal debits and credits and posting accumulated them correctly.

Canyon Fork Foods shows the following at March 31:

• GL Accounts Receivable control balance: $58,000
• Customer subledger totals: Ortiz Markets $21,000; Pine Catering $19,500; Sumner Grocer $16,000
• GL Cash balance (erroneous, after duplicate payroll): $33,700
• GL Wages Expense balance (erroneous, after duplicate payroll): $15,000
• Bank statement balance: $39,600
• Deposits in transit: $3,100
• Outstanding checks: $1,500
• Bank service charge not yet recorded in GL: $200
• Payroll batch PAY-03-31 posted twice; each posting was Dr Wages Expense $7,500 / Cr Cash $7,500. The bank processed only one $7,500 ACH withdrawal.

Tasks:

1. Calculate the AR control versus subledger discrepancy and state what it signals.
2. Complete the bank reconciliation to determine the correct GL Cash balance before the bank fee.
3. State correct March wage expense after removing the duplicate payroll posting.
4. Record the bank service charge and give the final correct GL Cash balance.
5. Explain why the trial balance could still balance even when AR, cash, and wages are wrong.

Solution

1. AR discrepancy

Subledger sum = 21,000 + 19,500 + 16,000 = $56,500

GL control = $58,000

Discrepancy = $1,500 (control higher than subledger)

This signals a posting integrity failure: a journal entry likely hit the AR control account without updating customer detail (or a customer balance was mistyped). Collections and financial reporting disagree until corrected.

2. Bank reconciliation (correct cash before bank fee)

Erroneous GL Cash: 33,700

Unexplained difference: 41,200 − 33,700 = $7,500 (matches one duplicate payroll credit)

3. Correct wage expense

Erroneous Wages Expense = $15,000 (7,500 × 2 postings)

Correct March wage expense = 15,000 − 7,500 = $7,500

Reversing entry for duplicate:

After reversal: Wages Expense = $7,500 ✓; GL Cash = 33,700 + 7,500 = $41,200 ✓

4. Bank service charge

Final correct GL Cash: 41,200 − 200 = $41,000 ✓

Adjusted bank after company records fee: 41,200 − 200 = $41,000 (no remaining reconciling items) ✓

5. Why the trial balance could still balance

Each payroll posting was a balanced pair (debit Wages Expense, credit Cash). Posting the batch twice still produced equal total debits and credits. The AR error likely paired with another account (for example, a credit to Service Revenue without subledger update) so the trial balance also footed. The bank fee was simply omitted (an equal debit and credit once recorded). None of these problems necessarily breaks debit-credit equality; they break economic accuracy, which is why subledger tie-outs, bank reconciliation, and expense analytics remain essential after posting.

Key takeaways

• Posting transfers journal entry amounts into GL accounts so each account shows debits, credits, and a running balance used for reporting.
• T-accounts and the formal GL use the same logic; subsidiary ledgers must tie to control accounts in the GL.
• Bank reconciliation explains differences between GL Cash and the bank statement and often surfaces duplicate or missing postings.
• A balanced trial balance confirms arithmetic equality only; cutoff errors, wrong-account postings, and duplicates can still misstate results.
• Harborline's January walkthrough previews the unadjusted trial balance you will build systematically in Lesson 5.

1. Pick a company you follow (or your own employer if applicable). When its 10-K (annual report filed with the U.S. Securities and Exchange Commission) describes a material weakness in internal controls, note whether the failure involved posting, subledger reconciliation, or cutoff. What stakeholder was most at risk?
2. Using the Harborline January entries, rebuild one account (Cash or AR) on paper without looking at the tables. Does your running balance match? If not, which journal line did you omit?
3. Continue to Lesson 5: Preparing an Unadjusted Trial Balance. You will assemble GL balances into a formal trial balance, learn what it proves and does not prove, and connect this Unit 2 checkpoint to Unit 3 adjusting entries.