MUMBAI: As scores of Amazon and Flipkart sellers prepare for the upcoming festive season, which accounts for a huge chunk of their annual sales, there’s lack of clarity and confusion on the ground about the compliance challenges that the rejigging of GST slabs could possibly bring forth. For one, some sellers are worried that the changed tax rates will take time to reflect on the systems of the platforms, given the heavy volumes of transactions during festive period. This, they said, would lead to discrepancies in platform invoicing (it will not reflect the updated tax rate) which will impact the GST filings of sellers. “All listings on marketplaces, apps and websites must reflect the new rates promptly. Billing, accounting and inventory software needs to be updated by platforms and sellers because any delay or error can lead to wrong tax filings and penalties,” said Sachin Manilal Gala, a seller registered with major platforms including Amazon and Flipkart.Every product sold on e-commerce platforms comes with a tax code, said another online seller Chirag Haria. Sellers can update the tax code but the issue is the timeline during which they should get it updated. “If 12% tax slab is removed and they are either moved to either 5% or 18% and say it comes into effect on September 22, when should the seller update the tax code of 5% or 18%? What about sales happening at 12 am on that day? In the past too, sellers have faced a similar issue whenever there were tax rate changes,” Haria said.Sellers are also worried about product returns. Given that most platforms tend to have up to seven-day return policy , consumers may choose to return the product and reorder to take advantage of the reduced GST rates. “There could be an issue with accounting for return. A product sold at 12% GST might get returned when the rate reduces to 5%,” said a seller.Queries sent to Amazon, Flipkart, Myntra and Meesho did not immediately elicit any response. The first leg of the biggest online sales starts a few days before Navaratri; sellers said that if the GST cuts are implemented closer to Diwali, it will hit their pre-Diwali festive sales.