Short answer: Static subjects can often be read from a second hand copy, but data-driven and current subjects are better from the latest edition.
Usually fine second hand
Books on ancient and medieval history, basic polity concepts and geography fundamentals change slowly. A clean second hand copy saves money without losing much.
Better to buy the latest
Economy, government schemes, environment data and current affairs go out of date quickly. Prefer the newest edition or a recent annual compilation.
Check before you order
Look at the edition year, the condition photos and any notes or highlighting. If something is unclear, ask the seller through the in-site chat before ordering.
Browse selling UPSC books if you have a set to pass on.
Frequently asked questions
Can I sell my UPSC books afterwards?
Yes, you can list them on Bookaao and the sale amount is settled to you after delivery, minus the platform fee.
How do I know the edition is current?
Check the edition and printing year on the listing or ask the seller.