Consumers selling their products on online portals like Quikr and OLX won’t be subjected to 1% tax collected at source under the Goods and Services tax regime, which came into force from July 1, tax officials told FE.This basically means that if consumers (people not engaged in selling and buying as trade) sell their old products on online portals, the latter will pay them the full amount and not deduct the 1% TCS. Consumers have been exempted from this tax because it is not their business activity.
“GST deals with supplies in the course or furtherance of business and therefore unless selling is not somebody’s business, GST will not apply to sales made by him. Recently, in a clarification, the central government stated that sale of second hand jewellery from a consumer to the jeweller is not in the course of business.

Source - http://www.financialexpress.com