Think of a business as a hospital. Every time a patient arrives, a receptionist logs the visit in an admission register before anything else happens — before the doctor's file is created, before billing, before discharge records. That admission register is the equivalent of the Book of Original Entry in accounting.
A Book of Original Entry is the first place where every financial transaction is recorded, in chronological order, as it happens. No transaction enters the ledger (the doctor's file, in our analogy) without first passing through a book of original entry. This is why these books are also called daybooks or prime entry books.
The principle behind this is straightforward: when hundreds of transactions happen daily, you need a chronological log before sorting them by account. The book of original entry gives you that log. From there, transactions are posted to the Ledger — which is the Book of Final Entry.
Here is the critical distinction the SSC CGL exam tests repeatedly:
The Journal is the most fundamental book of original entry. When a transaction does not fit into any specialised book, it goes into the Journal Proper (also called General Journal). But for high-volume, repetitive transactions — cash receipts and payments, credit purchases, credit sales — businesses maintain Subsidiary Books (also called Special Journals or Daybooks) to save time and effort.
The entire system exists because the double-entry principle requires every debit to have an equal credit. Books of original entry are where that two-sided logic is first applied before the amounts travel to their respective ledger accounts.
The full set of books a business typically maintains:
| Book | What it records | |---|---| | Journal Proper | Transactions not covered by any subsidiary book | | Cash Book | All cash receipts and payments; bank transactions | | Purchases Day Book | Credit purchases of goods only | | Sales Day Book | Credit sales of goods only | | Purchase Returns Book | Goods returned to suppliers | | Sales Returns Book | Goods returned by customers | | Bills Receivable Book | Bills of exchange received from debtors | | Bills Payable Book | Bills of exchange accepted by the business |
The Journal Proper records opening entries, closing entries, rectification entries, depreciation, bad debts written off, and transactions that do not fit elsewhere. Every entry has five components:
The narration below each entry explains why the entry was made.
The Cash Book is the one book every SSC CGL question on this topic references at least once. Look at what makes it special:
It records only cash and bank transactions — no credit transactions enter the Cash Book. But here is the dual purpose that examiners love to test: the Cash Book simultaneously acts as a journal (book of original entry) and as a ledger (it maintains the Cash Account and Bank Account directly). This means:
Three formats of Cash Book:
These books record only credit transactions in goods the business trades in. A common trap:
The amount recorded is always the net amount after trade discount. Trade discount is deducted before entry. Cash discount is never recorded in the subsidiary book — it appears only when payment is actually made.
This is the single most tested calculation point in this chapter:
Formula for amount recorded in Purchases/Sales Book:
Freight charges added to purchases are part of the cost payable, so they are included. Trade discount reduces the obligation, so it is deducted.
A Bill of Exchange drawn on a customer is first recorded in the Bills Receivable Book (B/R Book). The discount charged by the bank when a bill is discounted before maturity is calculated on the remaining period from the date of discounting to the maturity date.
When a bill is dishonoured, the customer's account is debited with the bill amount plus noting charges. Noting charges are legal expenses for officially recording the dishonour — they are recoverable from the defaulting party, so they become part of the customer's liability.
At the end of the period (daily, weekly, or monthly), the total of each subsidiary book is posted to the Ledger:
This is why subsidiary books reduce ledger work — individual transactions are not posted one by one; only the periodic total goes to the nominal account, while individual party accounts get their postings.
When listing subsidiary books from memory, use: Journal Proper, Cash Book, Purchases Book, Sales Book, Returns Inward (Sales Returns), Returns Outward (Purchases Returns), Bills Receivable, Bills Payable. In a question listing "books of accounts," immediately identify which are Books of Original Entry and which are statements (Trial Balance, Balance Sheet). Standard approach — scanning each option one by one: 20 seconds. With this pattern: under 5 seconds to eliminate Ledger, Trial Balance, Balance Sheet in one pass.
Whenever you see a purchase or sale question with a trade discount percentage, apply this two-step before doing anything else: (1) Multiply invoice amount by discount rate → get discount amount. (2) Subtract from invoice price → that net figure is what enters the book. If freight is mentioned as payable to the supplier, add it after step 2. The trap is adding cash discount at this stage — cash discount never appears in the subsidiary book entry. Standard method (reading all options, back-calculating): 45 seconds. This rule: 12 seconds — you do one subtraction, confirm the answer, move on.
Bill discount questions always give you the draw date, the maturity period, and the discounting date. The trick: find the maturity date first (draw date + months). Then count months from discounting date to maturity date — that is your remaining period. Plug into Bill × Rate/100 × Months/12. The common error is using the full bill period instead of the remaining period. If you anchor on "maturity date first, then count backward," you cannot make that error. Full calculation with period confusion: 60+ seconds including re-reading. Anchored method: under 20 seconds.
In every dishonour entry, the customer's account is debited for bill amount plus noting charges — no exceptions. Noting charges are always added because they are legally recoverable from the party in default. If an option shows only the bill amount or only the noting charges, eliminate it immediately. In a 4-option MCQ, this pattern eliminates two wrong options in under 3 seconds, leaving you to verify the arithmetic in the correct option only.
Any MCQ asking "which book serves as both a journal and a ledger" has exactly one answer: Cash Book. No other book has this dual nature. Similarly, if asked "which account does not need a separate ledger posting because its book serves as the ledger," the answer is Cash Account and Bank Account (maintained through the Cash Book). Recognising this pattern eliminates three wrong options instantly — standard 4-option question solved in under 6 seconds vs. 30 seconds of reasoning from scratch.
When you see a Books of Original Entry question in the exam, run this decision tree:
Step 1 — Is it a definition/classification question?
Step 2 — Is it a recording-amount question?
Step 3 — Is it a Cash Book dual-purpose question?
Step 4 — Is it a bill discount/dishonour question?
Step 5 — Which book to use?
Why this question: The most fundamental question on this topic — tests whether you know the precise definition and can distinguish Journal from Ledger.
Solving path: Apply the definition directly — the Journal is where transactions are recorded first, before any other book. The Ledger is Final Entry. Trial Balance and Balance Sheet are statements, not books. One elimination pass eliminates B, C, D. Answer: Journal.
Why this question: Tests the dual-purpose nature of the Cash Book — the most repeated conceptual point in this chapter.
Solving path: The Cash Book eliminates the need to maintain a separate Cash Account and Bank Account in the Ledger — so it functions as both. Balance Sheet (C) and Purchase Day Book (D) are unrelated to this function. Journal Proper (B) is a subset of the journal system, not what the Cash Book replaces. Answer: Ledger.
Why this question: Tests your ability to apply the TC-Net Rule — a calculation question that trips up candidates who add cash discount or forget freight.
Solving path: Credit sale → Sales Day Book. Trade discount = 10% of ₹15,000 = ₹1,500. Net amount = ₹15,000 − ₹1,500 = ₹13,500. Cash Book (B) is wrong because this is a credit sale. Journal Proper (D) is wrong because credit sales of goods go to Sales Day Book. Option C (₹15,000) is the trap for those who forget to deduct trade discount. Answer: Sales Journal; ₹13,500.
Why this question: Tests the Purchases Book calculation with freight charges — a more complex variant of the TC-Net Rule that adds a freight component.
Solving path: Step 1 — Trade discount: 15% of ₹50,000 = ₹7,500. Net price after discount = ₹50,000 − ₹7,500 = ₹42,500. Step 2 — Freight is payable to the supplier and forms part of the purchase cost, so add ₹1,500. Final entry = ₹42,500 + ₹1,500 = ₹44,000. Option B (₹42,500) is the trap for forgetting freight. Option D (₹50,000) is the trap for forgetting both adjustments. Answer: ₹44,000.
Why this question: Tests the Remaining Period Rule for bill discounting — a calculation question where using the wrong period is the single most common error.
Solving path: Maturity date = 1st March + 3 months = 1st June 2024. Discounting date = 1st April 2024. Remaining period = April + May = 2 months. Discount = ₹50,000 × 12/100 × 2/12 = ₹50,000 × 0.02 = ₹1,000. The trap option ₹1,500 is what you get if you use 3 months instead of 2. Answer: ₹1,000.
Confusing Ledger with Journal: Candidates call the Ledger a "Book of Original Entry" because it looks more detailed. It is not — it is the Book of Final Entry. Transactions go Journal → Ledger, not the other way.
Deducting cash discount in subsidiary books: Cash discount has nothing to do with the Purchases Book or Sales Book entry. It only appears when actual payment or receipt happens, either in the Cash Book's discount column or via a Journal Proper entry. If you deduct it during recording, your figures will be wrong.
Recording cash transactions in Purchases/Sales Day Book: If goods are purchased for cash, that transaction goes to the Cash Book — not the Purchases Day Book. The Purchases Day Book is exclusively for credit purchases of goods.
Recording asset purchases in the Purchases Day Book: A machine or furniture purchased on credit is not a trading good. It goes to the Journal Proper. Only goods in which the business trades belong in the Purchases Day Book.
Using the full bill period instead of the remaining period for discount calculation: The bank discounts the bill for the time remaining until maturity, not for the original duration of the bill. Always calculate maturity date first, then find remaining months from the discounting date.
Forgetting noting charges in dishonour entries: When a bill is dishonoured, the customer's account is debited for bill amount plus noting charges — not just the bill amount. Noting charges are legally recoverable from the defaulter, so they attach to the customer's liability immediately.