Q.Purchase Day Book is actually a

From Your Daily Life to the Ledger

Think about your own pocket money. You don't record every single expense in a grand "life ledger" the moment it happens. Instead, you might jot down small notes on your phone, keep a few receipts in your wallet, or scribble on a scrap of paper. At the end of the week, you sit down and sort those notes into categories: "ate out," "bought stationery," "recharged phone." Only then do you update your main spending record.

That's exactly what a Subsidiary Journal does in accounting.

A business has hundreds of transactions every day. Imagine writing each one directly into the main ledger — it would be chaotic, error-prone, and impossible to manage. So accountants use subsidiary journals (also called subsidiary books or special journals) as the first point of entry. Each subsidiary journal is dedicated to one type of recurring transaction.

The Precise Meaning

A Subsidiary Journal is a book of original entry used to record transactions of a similar nature before they are posted to the ledger. Instead of one single journal for everything, we have separate books for:

• Cash Book – for all cash and bank transactions
• Purchases Book – for credit purchases of goods
• Sales Book – for credit sales of goods
• Purchases Return Book – for goods returned to suppliers
• Sales Return Book – for goods returned by customers
• Bills Receivable Book – for bills of exchange received
• Bills Payable Book – for bills of exchange accepted
• Journal Proper – for the remaining, infrequent transactions (like opening entries, rectification entries, etc.)

Why It Matters

Three reasons, and they are all about efficiency and control.

1. Division of Labour. In a large business, one person can handle the Sales Book, another the Purchases Book, and a third the Cash Book. They work simultaneously without stepping on each other's toes. The main ledger is updated later, in bulk.

2. Quick Reference. If a customer claims they returned goods last week, you don't flip through hundreds of journal entries. You open the Sales Return Book and find the record in seconds. Each subsidiary book is a dedicated file.

3. Error Detection. When totals from subsidiary books are posted to the ledger, the arithmetic is checked at the book level. A mistake in the Purchases Book is caught before it spreads to the ledger and trial balance.

Accounting Treatment: The Debit-Credit Logic

Here is the key rule: The subsidiary journal itself is not debited or credited. It is a book of first entry. The debit and credit happen when the totals are posted to the ledger accounts.

Let's take the Purchases Book as an example.

Step 1: Recording in the Purchases Book

When goods are bought on credit, the entry in the Purchases Book is simply a list: date, supplier's name, invoice number, and amount. No debit/credit here — just a record.

Step 2: Posting to the Ledger

At the end of the month, the total of the Purchases Book is posted:

• Debit the Purchases Account (in the ledger) — because purchases are an expense, and expenses increase on the debit side.
• Credit each Supplier's Personal Account (in the ledger) — because the business owes money to each supplier, and liabilities increase on the credit side.

The Same Logic for Other Books

The Format of a Subsidiary Journal

Let me show you the Purchases Book format. This is the standard proforma you will see in your textbook and in exams.

Purchases Book (also called Purchases Journal) …