Q.Enter the following transactions of a trader in the Purchase Book, and show the ledger postings (assume GST @ 12%, i.e. CGST 6% + SGST 6%):
2026 Sept 2 — Purchased goods from Anand Traders, list price ₹30,000, less trade discount 10%, Invoice No. 71.
2026 Sept 9 — Purchased goods from Bhagwat & Co., list price ₹12,000, no trade discount, Invoice No. 145.
2026 Sept 16 — Purchased goods from Chetan Stores, list price ₹18,000, less trade discount 5%, Invoice No. 302.

This is a standard Purchase Book preparation problem, requiring the trade discount to be deducted first and GST computed on the resulting taxable value for each supplier separately.

After deducting trade discount, the taxable values are ₹27,000 (Anand), ₹12,000 (Bhagwat) and ₹17,100 (Chetan), giving total taxable value ₹56,100, total CGST ₹3,366, total SGST ₹3,366, and total net amount ₹62,832.

Working: Anand Traders — trade discount = 10% of ₹30,000 = ₹3,000; taxable value = ₹27,000; CGST 6% = ₹1,620; SGST 6% = ₹1,620; net = ₹30,240. Bhagwat & Co. — no discount; taxable value = ₹12,000; CGST = ₹720; SGST = ₹720; net = ₹13,440. Chetan Stores — trade discount = 5% of ₹18,000 = ₹900; taxable value = ₹17,100; CGST = ₹1,026; SGST = ₹1,026; net = ₹19,152.

Purchase Book, for September 2026

Check: 30,240 + 13,440 + 19,152 = ₹62,832, and separately 56,100 + 3,366 + 3,366 = ₹62,832 — both routes agree.

Ledger postings: Purchases A/c ... Dr ₹56,100; Input CGST A/c ... Dr ₹3,366; Input SGST A/c ... Dr ₹3,366; To Anand Traders A/c ₹30,240; To Bhagwat & Co. A/c ₹13,440; To Chetan Stores A/c ₹19,152.

Compute each row independently (Gross → less Trade Discount → Taxable Value → +CGST +SGST → Net Amount), THEN total each column down — never total the gross amounts and apply one blended discount/tax rate to the total, since discount and tax rates can differ supplier to supplier.

A common arithmetic slip is computing trade discount or GST on the WRONG base — trade discount is always a percentage of the gross list price, and GST (6%+6%) is always computed on the taxable value AFTER trade discount, never on the original gross price.