In the normal course of business, a document is produced each time a transaction occurs. Sales and purchases usually have invoices or receipts. Deposit slips are produced when lodgements (deposits) are made to a bank account. Cheques are written to pay money out of the account. Bookkeeping involves recording the details of all of these source documents into multi-column journals (also known as a books of first entry or daybooks). For example, all credit sales are recorded in the Sales Journal, all Cash Payments are recorded in the Cash Payments Journal. Columns in the journal, normally correspond to an account. In the single entry system, each transaction is recorded only once. Most individuals who balance their cheque-book each month are using such a system, and most personal finance software follows this approach.
After a certain period, typically a month, the columns in each journal are each totalled to give a summary for the period. Using the rules of double entry, these journal summaries are then transferred to their respective accounts in the ledger, or book of accounts. The process of transferring summaries or individual transactions to the ledger is called Posting. Once the posting process is complete, accounts kept using the "T" format undergo balancing which is simply a process to arrive at the balance of the account.
To quickly check that the posting process was done correctly, a working document called an unadjusted trial balance is created. In its simplest form, this is a three column list. The first column contains the names of those accounts in the ledger which have a non-zero balance. If an account has a debit balance, the balance amount is copied into column two (the debit column). If an account has a credit balance, the amount is copied into column three (the credit column). The debit column is then totaled and then the credit column is totaled. The two totals must agree - this agreement is not by chance - it happens because under the double-entry rules, whenever there is a posting, the debits of the posting equal the credits of the posting. If the two totals do not agree therefore, an error has been made in either the journals or made during the posting process. The error(s) must be located and rectified and the totals of debit column and credit column re-calculated to check for agreement before any further processing can take place.
Once there are no errors, the accountant produces a number of adjustments and changes the balance amounts of some of the accounts. For example, the "Inventory" account and "Office Supplies" asset accounts are changed to bring them into line with the actual numbers counted during a stock take. At the same time, the expense accounts associated with usage of inventory and with the usage of office supplies are adjusted. Other refinements necessary to ensure that accounting principles are complied with are also done at this time. This results in a listing called, not surprisingly, the adjusted trial balance. It is the accounts in this list and their corresponding debit or credit balances that are used to prepare the financial statements.
Finally financial statements are drawn from the trial balance, which may include:
- the income statement, also known as a statement of financial results, profit and loss statement, or simply P&L
- the balance sheet
- the cash flow statement
- the statement of retained earnings