Double-entry bookkeeping system

A double-entry bookkeeping system is a set of rules for recording financial information in a financial accounting system in which every transaction or event changes at least two different nominal ledger accounts.

The name derives from the fact that financial information used to be recorded using pen and ink in paper books – hence "bookkeeping" (whereas now it's recorded mainly in computer systems) and that these books were called journals and ledgers (hence nominal ledger, etc.) – and that each transaction was entered twice (hence "double-entry"), with one side of the transaction being called a debit and the other a credit.

It was first codified in the 15th century by Luca Pacioli. In deciding which account has to be debited and which account has to be credited, the golden rules of accounting are used. This is also accomplished using the accounting equation: Equity = Assets - Liabilities. The accounting equation serves as an error detection tool. If at any point the sum of debits for all accounts does not equal the corresponding sum of credits for all accounts, an error has occurred. It follows that the sum of debits and the sum of the credits must be equal in value.

Double-entry bookkeeping is not a guarantee that no errors have been made – for example, the wrong ledger account may have been debited or credited, or the entries completely reversed.

Contents 1 Accounting entries 2 History 3 Approaches 3.1 Traditional approach 3.2 Accounting equation approach 4 Books of accounts 5 Debits and credits 6 Double entry example 6.1 Purchase invoice daybook 6.2 Bank payments daybook 6.3 Supplier ledger cards 6.3.1 Sales/customers 6.3.1.1 Sales daybook 6.3.1.2 Customer ledger cards 6.3.2 General (nominal) ledger 6.3.2.1 Bank account 6.3.2.2 Unadjusted trial balance 6.3.2.3 Profit-and-loss statement and balance sheet 7 See also 8 Notes and references 9 Further reading 10 External links

Accounting entries

In the double-entry accounting system, each accounting entry records related pairs of financial transactions for asset, liability, income, expense, or capital accounts. Recording of a debit amount to one account and an equal credit amount to another account results in total debits being equal to total credits for all accounts in the general ledger. If the accounting entries are recorded without error, the aggregate balance of all accounts having positive balances will be equal to the aggregate balance of all accounts having negative balances. Accounting entries that debit and credit related accounts typically include the same date and identifying code in both accounts, so that in case of error, each debit and credit can be traced back to a journal and transaction source document, thus preserving an audit trail. The rules for formulating accounting entries are known as "Golden Rules of Accounting". The accounting entries are recorded in the "Books of Accounts". Regardless of which accounts and how many are impacted by a given transaction, the fundamental accounting equation A = L + OE will hold, i.e. assets equals liabilities plus owner's equity.

History

The earliest extant records that follow the modern double-entry form are those of Amatino Manucci, a Florentine merchant at the end of the 13th century.^[1] Some sources suggest that Giovanni di Bicci de' Medici introduced this method for the Medici bank in the 14th century. By the end of the 15th century, the merchant venturers of Venice used this system widely. Luca Pacioli, a Franciscan friar and collaborator of Leonardo da Vinci, first codified the system in a mathematics textbook of 1494.^[2] Pacioli is often called the "father of accounting" because he was the first to publish a detailed description of the double-entry system, thus enabling others to study and use it.^[3][4] There is however controversy among scholars lately that Benedikt Kotruljević wrote the first manual on a double-entry bookkeeping system in his 1458 treatise Della mercatura e del mercante perfetto.^{[5][6][7][8][9][10]}

Approaches

There are two different approaches to the double entry system of bookkeeping. They are Traditional Approach and Accounting Equation Approach. Irrespective of the approach used, the effect on the books of accounts remain the same, with two aspects (debit and credit) in each of the transactions.

Traditional approach

This approach is used in Britain in which accounts are classified as real, personal, and nominal accounts. Real accounts are assets. Personal accounts are liabilities and owners' equity and represent people and entities that have invested in the business. Nominal accounts are revenue, expenses, gains, and losses. Transactions are entered in the books of accounts by applying the following golden rules of accounting:

1. Personal account: Debit the receiver and credit the giver
2. Real account: Debit what comes in and credit what goes out
3. Nominal account: Debit all expenses & losses and credit all incomes & gains^[11]

Accounting equation approach

This approach is also called as the American approach. Under this approach transactions are recorded based on the accounting equation, i.e., Assets = Liabilities + Capital. The accounting equation is a statement of equality between the debits and the credits. The rules of debit and credit depend on the nature of an account. For the purpose of the accounting equation approach, all the accounts are classified into the following five types: assets, liabilities, income/revenues, expenses, or capital gains/losses.

If there is an increase or decrease in one account, there will be equal decrease or increase in another account. There may be equal increases to both accounts, depending on what kind of accounts they are. There may also be equal decreases to both accounts. Accordingly, the following rules of debit and credit in respect to the various categories of accounts can be obtained. The rules may be summarised as below:

1. Assets Accounts: debit increases in assets and credit decreases in assets
2. Capital Account: credit increases in capital and debit decreases in capital
3. Liabilities Accounts: credit increases in liabilities and debit decreases in liabilities
4. Revenues or Incomes Accounts: credit increases in incomes and gains and debit decreases in incomes and gains
5. Expenses or Losses Accounts: debit increases in expenses and losses and credit decreases in expenses and losses

Books of accounts

Each financial transaction is recorded in at least two different nominal ledger accounts within the financial accounting system, so that the total debits equals the total credits in the General Ledger, i.e. the accounts balance. This is a partial check that each and every transaction has been correctly recorded. The transaction is recorded as a "debit entry" (Dr.) in one account, and a "credit entry" (Cr.) in a second account. The debit entry will be recorded on the debit side (left-hand side) of a General ledger and the credit entry will be recorded on the credit side (right-hand side) of a General ledger account. If the total of the entries on the debit side of one account is greater than the total on the credit side of the same nominal account, that account is said to have a debit balance.

Double entry is used only in nominal ledgers. It is not used in daybooks (journals), which normally do not form part of the nominal ledger system. The information from the daybooks will be used in the nominal ledger and it is the nominal ledgers that will ensure the integrity of the resulting financial information created from the daybooks (provided that the information recorded in the daybooks is correct).

The reason for this is to limit the number of entries in the nominal ledger: entries in the daybooks can be totalled before they are entered in the nominal ledger. If there are only a relatively small number of transactions it may be simpler instead to treat the daybooks as an integral part of the nominal ledger and thus of the double-entry system.

However as can be seen from the examples of daybooks shown below, it is still necessary to check, within each daybook, that the postings from the daybook balance.

The double entry system uses nominal ledger accounts. From these nominal ledger accounts a trial balance can be created. The trial balance lists all the nominal ledger account balances. The list is split into two columns, with debit balances placed in the left hand column and credit balances placed in the right hand column. Another column will contain the name of the nominal ledger account describing what each value is for. The total of the debit column must equal the total of the credit column.

Debits and credits

Double-entry bookkeeping is governed by the accounting equation. If revenue equals expenses, the following (basic) equation must be true:

assets = liabilities + equity

For the accounts to remain in balance, a change in one account must be matched with a change in another account. These changes are made by debits and credits to the accounts. Note that the usage of these terms in accounting is not identical to their everyday usage. Whether one uses a debit or credit to increase or decrease an account depends on the normal balance of the account. Assets, Expenses, and Drawings accounts (on the left side of the equation) have a normal balance of debit. Liability, Revenue, and Capital accounts (on the right side of the equation) have a normal balance of credit. On a general ledger, debits are recorded on the left side and credits on the right side for each account. Since the accounts must always balance, for each transaction there will be a debit made to one or several accounts and a credit made to one or several accounts. The sum of all debits made in any transaction must equal the sum of all credits made. After a series of transactions, therefore, the sum of all the accounts with a debit balance will equal the sum of all the accounts with a credit balance.

Debits and credits are numbers recorded as follows:

• Debits are recorded on the left side of a T account in a ledger. Debits increase balances in asset accounts and expense accounts and decrease balances in liability accounts, revenue accounts, and capital accounts.
• Credits are recorded on the right side of a T account in a ledger. Credits increase balances in liability accounts, revenue accounts, and capital accounts, and decrease balances in asset accounts and expense accounts.
• Debit accounts are asset and expense accounts that usually have debit balances, i.e. the total debits usually exceeds the total credits in each debit account.
• Credit accounts are revenue (income, gains) accounts and liability accounts that usually have credit balances.

	Debit	Credit
Asset	Increase	Decrease
Liability	Decrease	Increase
Income (revenue)	Decrease	Increase
Expense	Increase	Decrease
Capital	Decrease	Increase

Double entry example

In this example the following will be used:

Books of prime entry (Books of original entry)

• Sales Invoice Daybook (records customer invoices)
• Bank Receipts Daybook (records customer & non customer receipts)
• Cash book
• Return inwards day book
• Return outwards day book
• Purchase Invoice Daybook (records supplier invoices)
• Bank Payments Daybook (records supplier & non supplier payments)

The books of prime entry are where transactions are first recorded. They are not part of the Double-entry system.

Ledger Cards

• Customer Ledger Cards
• Supplier Ledger Cards
• General Ledger (Nominal Ledger)
• Bank Account Ledger
• Trade Creditors Ledger
• Trade Debtors Ledger

Purchase invoice daybook

Purchase Invoice Daybook

Date	Supplier Name	Reference	Amount	Electricity	Widgets
10 July 2006	Electricity Company	PI1	1000	1000
12 July 2006	Widget Company	PI2	1600		1600
			-------	-------	-------
		Total	2600	1000	1600
			====	====	====
			Credit	Debit	Debit
			Trade	Electricity	Widgets
			control a/c	a/c	a/c

Each individual line is posted as follows:

• The amount value is posted as a credit to the individual supplier's ledger a/c
• The analysis amount is posted as a debit to the relevant general ledger a/c

From example above:

• Line 1 – Amount value 1000 is posted as a credit to the Supplier's ledger a/c ELE01-Electricity Company
• Line 2 – Amount value 1600 is posted as a credit to the Supplier's ledger a/c WID01-Widget Company

The totals of each column are posted as follows:

• Amount total value 2600 posted as a credit to the Trade creditors control a/c
• Electricity total value 1000 posted as a debit to the Electricity General Ledger a/c
• Widget total value 1600 posted as a debit to the Widgets General Ledger a/c

Double-entry has been observed because Dr = 2600 and Cr = 2600.

Bank payments daybook

The payments book is not part of the double-entry system.

Bank Payments Daybook

Date	Supplier Name	Reference	Amount	Suppliers	Wages
17 July 2006	Electricity Company	BP701	1000	1000
19 July 2006	Widget Company	BP702	900	900
28 July 2006	Owner's Wages	BP703	400		400
			-------	-------	-------
		Total	2300	1900	400
			====	====	====
			Credit	Debit	Debit
			Bank	Trade	Wages
			Account	Creditors	control a/c
				control a/c

Keys: PI = Purchase Invoice, BP = Bank Payment

Each individual line is posted as follows:

• The amount value is posted as a debit to the individual supplier's ledger a/c.
• The analysis amount is posted as a credit to the relevant general ledger a/c.

From example above:

• Line 1 – Amount value 1000 is posted as a debit to the Supplier's ledger a/c ELE01-Electricity Company.
• Line 2 – Amount value 900 is posted as a debit to the Supplier's ledger a/c WID01-Widget Company.

The totals of each column are posted as follows:

• Amount total value 2300 posted as a credit to the Bank Account.
• Trade Creditors total value 1900 posted as a debit to the Trade creditors control a/c.
• Other total value 400 posted as a debit to the Wages control a/c.

Double-entry has been observed because Dr = 2300 and Cr = 2300.

The daybooks are the key documents (books) to the double entry system. From these daybooks we create the ledger accounts. Each transaction will be recorded in at least two ledger accounts.

Supplier ledger cards

Supplier Ledger Cards

A/c Code: ELE01 – Electricity Company
Date	Details	Reference	Amount	Date	Details	Reference	Amount
17 July 2006	Bank Payments Daybook	BP701	1000	10 July 2006	Invoice	PI1	1000
31 July 2006	Balance c/d		0
			-------				-------
			1000				1000
			====				====
				1 August 2006	Balance b/d		0
A/c Code: WID01 – Widget Company
Date	Details	Reference	Amount	Date	Details	Reference	Amount
19 July 2006	Bank Payments Daybook	BP702	900	12 July 2006	Invoice	PI2	1600
31 July 2006	Balance c/d		700
			-------				-------
			1600				1600
			====				====
				1 August 2006	Balance b/d		700

Sales/customers

Sales daybook

Sales Invoice Daybook

Date	Customer Name	Reference	Amount	Parts	Service
2 July 2006	JJ Manufacturing	SI1	2500	2500
29 July 2006	JJ Manufacturing	SI2	3200		3200
			-------	-------	-------
		Total	5700	2500	3200
			====	====	====
			Debit	Credit	Credit
			Trade	Sales	Sales
			debtors	Parts	Service
			control a/c	a/c	a/c

Each individual line is posted as follows:

• The amount value is posted as a debit to the individual customer's ledger a/c.
• The analysis amount is posted as a credit to the relevant general ledger a/c.

From example above:

• Line 1 – Amount value 2500 is posted as a debit to the Customer's ledger a/c JJM01-JJ Manufacturing.
• Line 2 – Amount value 3200 is posted as a debit to the Customer's ledger a/c JJM01-JJ Manufacturing.

The totals of each column are posted as follows:

• Amount total value 5700 posted as a debit to the Trade debtors control a/c.
• Sales-parts total value 2500 posted as a credit to the Sales parts a/c.
• Sales-service total value 3200 posted as a credit to the Sales service a/c.

Double-entry has been observed because Dr = 5700 and Cr = 5700.

Customer ledger cards

Customer Ledger cards are not part of the Double-entry system. They are for memorandum purposes only. They allow you to know the total amount an individual customer owes you.

CUSTOMER LEDGER CARDS

A/c Code: JJM01 – JJ Manufacturing
Date	Details	Reference	Amount	Date	Details	Reference	Amount
2 July 2006	Sales invoice daybook	SI1	2500	20 July 2006	Bank receipts daybook	BR1	2500
29 July 2006	Sales invoice daybook	SI2	3200	31 July 2006	balance c/d		3200
			-------				-------
			5700				5700
			====				====
1 August 2006	Balance b/d		3200

General (nominal) ledger

GENERAL (NOMINAL) LEDGER

Sales parts
Date	Details	Reference	Amount	Date	Details	Reference	Amount
31 July 2006	Balance	c/d	2500	2 July 2006	Sales invoice daybook	SDB	2500
			-------				-------
			2500				2500
			====				====
				1 August 2006	Balance	b/d	2500
Sales service
Date	Details	Reference	Amount	Date	Details	Reference	Amount
31 May 2006	Balance	c/d	3200	29 July 2006	Sales invoice daybook	SDB	3200
			-------				-------
			3200				3200
			====				====
				1 June 2010	Balance	b/d	3200
Electricity
Date	Details	Reference	Amount	Date	Details	Reference	Amount
10 May 2010	Electricity Co.	PDB	1000	30 May 2010	Balance	c/d	1000
			-------				-------
			1000				1000
			====				====
1 June 2010	Balance	b/d	1000
Water
Date	Details	Reference	Amount	Date	Details	Reference	Amount
12 May 2010	water Co.	Pdb	1600	31 May 2010	Balance	c/d	1600
			-------				-------
			1600				1600
			====				====
1 August 2010	Balance	b/d	1600
Other a/c
Date	Details	Reference	Amount	Date	Details	Reference	Amount
28 July 2006	Owner's Wages	BPDB	400	31 July 2006	Balance	c/d	400
			-------				-------
			400				400
			====				====
1 August 2006	Balance	b/d	400
Bank Control A/c
Date	Details	Reference	Amount	Date	Details	Reference	Amount
31 July 2006	Bank receipts daybook	BRDB	2500	31 July 2006	Bank payments daybook	BPDB	2300
				31 July 2006	Balance	c/d	200
			-------				-------
			2500				2500
			====				====
1 August 2006	Balance	b/d	200
Trade Debtors Control A/c
Date	Details	Reference	Amount	Date	Details	Reference	Amount
1 July 2006	Balance	b/d	0	31 July 2006	Bank receipts daybook	BRDB	2500
31 July 2006	Sales Invoice Daybook	SDB	5700	31 July 2006	Balance	c/d	3200
			-------				-------
			5700				5700
			====				====
1 August 2006	Balance	b/d	3200
Trade Creditors Control A/c
Date	Details	Reference	Amount	Date	Details	Reference	Amount
31 July 2006	Bank Payments Daybook	BPDB	1900	1 July 2006	Balance	b/d	0
31 July 2006	Balance	c/d	700	31 July 2006	Purchase Daybook	PDB	2600
			-------				-------
			2600				2600
			====				====
				1 August 2006	Balance	b/d	700

The customers ledger cards shows the breakdown of how the trade debtors control a/c is made up. The trade debtors control a/c is the total of outstanding debtors and the customer ledger cards shows the amount due for each individual customer. The total of each individual customer account added together should equal the total in the trade debtors control a/c.

The supplier ledger cards shows the breakdown of how the trade creditors control a/c is made up. The trade creditors control a/c is the total of outstanding creditors and the suppliers ledger cards shows the amount due for each individual supplier. The total of each individual supplier account added together should equal the total in the trade creditors control a/c.

Each Bank a/c shows all the money in and out through a bank. If you have more than one bank account for your company you will have to maintain separate bank account ledgers in order to complete bank reconciliation statements and be able to see how much is left in each account.

Bank account

Bank A/c
Date	Details	Reference	Amount	Date	Details	Reference	Amount
20 July 2006	Bank Receipts Day Book	BR1	2500	17 July 2006	Bank Payments Daybook	BP701	1000
				19 July 2006	Bank Payments Daybook	BP702	900
				28 July 2006	Bank Payments Daybook	BP703	400
				31 July 2006	Balance	c/d	200
			-------				-------
			2500				2500
			====				====
1 August 2006	Balance	b/d	200

Unadjusted trial balance

Trial balance as at 31 July 2006
A/c description	Debit	Credit
Sales-parts		2500
Sales-service		3200
Widgets	1600
Electricity	1000
Other	400
Bank	200
Trade Debtors Control A/c	3200
Trade Creditors Control A/c		700
	-------	-------
	6400	6400
	=====	=====
Both sides must have the same overall total
Debits = Credits.

The individual customer accounts are not to be listed in the trial balance, as the Trade debtors control a/c is the summary of each individual customer a/c.

The individual supplier accounts are not to be listed in the trial balance, as the Trade creditors control a/c is the summary of each individual supplier a/c.

Important note: this example is designed to show double entry. There are methods of creating a trial balance that significantly reduce the time it takes to record entries in the general ledger and trial balance.

Profit-and-loss statement and balance sheet

Profit and loss statement

for the month ending 31 July 2006
		Dr
x	Sales
x	Sales-parts	2500
x	Sales-service	3200
x		-------
x		5700
x	Widgets	1600
x		-------
x	Gross Profit	4100
x	Less expenses
x	Electricity	1000
x	Other	400
x		-------
x		1400
x		-------
x	Net Profit	2700
x		====

Balance sheet

as at 31 July 2006
			Dr
x	Current Assets
x	Bank A/c		200
x	Trade Debtors		3200
x			-------
x			3400
x	Current Liabilities
x	Trade Creditors		700
x			-------
x			700
x			-------
x	Net Current Assets		2700
x			====
x	Capital & Reserves
x	Revenue Reserves a/c		2700
x			-------
x			2700
x			====

See also

• Nostro and vostro accounts
• Single-entry bookkeeping system
• Momentum accounting and triple-entry bookkeeping

Notes and references

Further reading

• Gleeson-White, Jane (November 2011). Double Entry. Allen & Unwin. ISBN 9781741757552. 

External links

• A Concise Explanation of the Accounting Equation
• A double entry GnuCash How-to
• Bean Counter's bookkeeping tutorial
• Bookkeeping Terms
• GnuCash data entry concepts