Closing profit and loss accounts at year end is one of those accounting steps that feels technical until it goes wrong. Then it suddenly explains why the trial balance, opening balances and retained earnings do not seem to line up.

The short version is simple: income and expense accounts are temporary. They measure what happened during one accounting period. At year end, they are closed so the next period starts with a clean profit and loss account. The effect of the profit or loss does not disappear. It moves into the balance sheet, normally through retained earnings or the profit and loss account reserve.

This matters when preparing annual accounts and notes , filing a Company Tax Return , or setting opening balances when changing software .

The basic idea

QuestionPractical answer
What is closed?Income and expense accounts in the nominal ledger.
What is not closed?Balance sheet accounts such as bank, debtors, creditors, VAT, Corporation Tax and share capital.
Where does profit go?Into capital and reserves, usually retained earnings or the profit and loss account reserve.
Why can two years look different?One year may show open profit and loss balances, while the next year only carries forward balance sheet accounts.
What is the common mistake?Treating the full profit for the year as a suspense or rounding difference.

Profit and loss accounts close into retained earnings

Profit and loss accounts are period accounts

A balance sheet account is a position at a date. If the bank account is £10,000 at 31 March, the next accounting period should normally open with the same £10,000 bank balance.

Profit and loss accounts are different. Turnover, cost of sales, wages, rent, depreciation, interest and Corporation Tax expense belong to a period. Once that period is closed, those accounts should not keep their old balances as the starting point for the next year.

That does not mean the company loses the profit. It means the profit is no longer sitting across the income and expense accounts. It is now part of the company’s reserves.

Example 1: One sale, no other entries

Imagine a company has only one transaction in the year:

AccountDebitCredit
Bank£10,000
Sales£10,000

Before the year-end close, the trial balance is balanced. Bank has a debit balance of £10,000, and sales has a credit balance of £10,000.

At the start of the next year, however, only the balance sheet account should carry forward:

AccountOpening balance next year
Bank£10,000
Sales£0

If you only look at the bank account, it can look as if the other side has vanished. It has not. The £10,000 profit must be transferred to reserves:

AccountBalance after close
Bank£10,000 debit
Retained earnings£10,000 credit
Income and expense accounts£0

The money is still in the company. The accounting presentation has changed from an in-year profit to accumulated reserves.

Example 2: Profit after Corporation Tax

Now take a more realistic small limited company:

Profit and loss accountDebitCredit
Turnover£240,000
Cost of sales£82,000
Wages and salaries£70,000
Rent and premises costs£18,000
Bank interest received£500
Corporation Tax expense£14,630
Profit after tax£55,870

Before closing, the profit is spread across several income and expense accounts. A year-end close brings those balances to zero and leaves the after-tax profit ready to move into reserves.

One simplified closing entry would be:

Closing lineDebitCredit
Turnover£240,000
Bank interest received£500
Cost of sales£82,000
Wages and salaries£70,000
Rent and premises costs£18,000
Corporation Tax expense£14,630
Profit and loss summary£55,870

Then the profit is moved to reserves:

Transfer to reservesDebitCredit
Profit and loss summary£55,870
Retained earnings£55,870

Different accounting systems use different account names. Some use “current year earnings”, “profit and loss account reserve”, “retained earnings” or an automatic year-end journal. The labels matter less than the control: income and expense accounts should be zero for the new period, and capital and reserves should include the profit after tax.

Example 3: Profit with dividends

Dividends are not an expense in the company’s profit and loss account. They are distributions of after-tax profit. That distinction matters.

Assume the company has profit after tax of £55,870 and declares £20,000 of dividends after checking that it has sufficient distributable profits.

Movement in reservesDebitCredit
Profit transferred to retained earnings£55,870
Dividends declared£20,000
Net increase in retained earnings£35,870

If dividends are posted as a normal expense, the profit and loss account will be wrong. If dividends are not reflected in reserves at all, the balance sheet will be wrong. They belong in the movement in equity/reserves, supported by proper approval and dividend records.

Example 4: A loss is closed too

Losses follow the same logic with the opposite sign. Suppose a company has:

AccountDebitCredit
Turnover£90,000
Expenses£130,000
Loss for the year£40,000

At year end, the loss is transferred to retained earnings:

Transfer of lossDebitCredit
Retained earnings£40,000
Profit and loss summary£40,000

The new year still starts with zero income and expense balances. The accumulated loss is shown in reserves instead.

Why this causes trouble when changing accounting software

Opening balances are usually balance sheet balances. They are not a copy of last year’s entire trial balance.

Problems appear when the previous system has not finished the year-end close. The old trial balance may still show income and expense account balances, while the new software expects only balance sheet accounts as the starting point.

Export or reportWhat it may showWhat it means
Trial balance before year-end closeIncome and expense balances still openProfit or loss has not yet been transferred to reserves.
Opening balances in new softwareBank, debtors, creditors, VAT, tax, capital and reservesThe new year starts from the balance sheet only.
Difference equal to profit after taxA large unexplained imbalanceUsually a year-end close or retained earnings issue, not a rounding difference.

Imagine this simplified position at 31 March:

Balance sheet areaAmount
Bank and debtors£85,000
Creditors and tax liabilities£25,000
Share capital£100
Retained earnings before current year£24,900
Current year profit not yet closed£35,000

If the £35,000 current year profit is not transferred into reserves, the opening balance in the new system will not balance. The correct fix is not to post £35,000 to suspense. The correct fix is to decide whether the old year should be closed in the previous software or carried into the new system and closed there.

Three clean ways to handle the transition

MethodWhen it works bestWhat happens to the profit or loss
Close the old year before migrationThe accounts are final or nearly finalRetained earnings already includes the result before opening balances are imported.
Import the unfinished year and close it in ReAIYou want the year-end work completed in the new systemIncome and expense balances remain visible until the year-end close is done.
Import final opening balances onlyYou have a post-close trial balanceProfit and loss accounts are not imported as opening balances.

Whichever route you choose, keep the audit trail. UK companies must keep accounting records and the supporting information needed to prepare annual accounts and the Company Tax Return.

Control checks before you post a difference

Use these checks before treating an imbalance as suspense, rounding or a generic adjustment:

CheckWhat to look for
Sum all income and expense accountsDo they net to zero after the year-end close?
Check current year earningsIs the profit or loss sitting in a temporary equity account?
Reconcile retained earningsDoes opening retained earnings plus profit after tax less dividends equal closing retained earnings?
Compare closing and opening balancesDoes the unexplained difference equal the current year profit or loss?
Review Corporation TaxHas the tax charge and tax creditor been posted before the profit transfer?
Check dividendsAre dividends recorded as distributions, not as ordinary expenses?

How ReAI should treat the year-end close

In ReAI, the practical goal is to keep three things connected:

  1. The profit and loss account explains performance for the year.
  2. The balance sheet explains the company’s position at the year end.
  3. The year-end close explains how profit or loss moves into reserves.

If you are moving from another accounting system, first confirm which version of the numbers you have. A pre-close trial balance and a post-close trial balance are both useful, but they are not the same document.

Common mistakes

MistakeWhy it causes troubleBetter treatment
Posting the profit difference to suspenseIt hides that the year-end close is incompleteTransfer profit or loss to retained earnings.
Importing a pre-close trial balance as opening balancesIncome and expense accounts carry into the new yearImport only balance sheet accounts, or close the old year in ReAI.
Treating dividends as expensesProfit and Corporation Tax reporting are distortedRecord dividends as distributions from reserves.
Ignoring Corporation Tax before closing profitRetained earnings is overstatedPost the Corporation Tax expense and liability first.
Losing the old reports after migrationThe opening position cannot be explained laterArchive the trial balance, nominal ledger, accounts and tax support.

In summary

At year end, profit and loss accounts are cleared because they belong to one accounting period. The profit or loss is not lost. It moves into the balance sheet through retained earnings or the profit and loss account reserve.

When changing accounting software, always ask one question before posting a large difference: are we looking at numbers before or after the year-end close? If the difference equals the current year profit or loss, the issue is usually retained earnings, not rounding.

Sources and further reading