Mumbai: As the Indian arms of the Big Four race to deploy artificial intelligence, tax is emerging as the first major battleground, with firms redesigning workflows in a profession where large teams of consultants have long helped clients navigate the complex regulatory maze of GST, direct taxes, customs duties, transfer pricing and litigation.The level of adoption is high across companies as AI is increasingly being used by tax consultants to do routine, preparatory and research-intensive work.At PwC India, around 1,500 employees generate more than 10,000 AI queries daily. At Deloitte India, up to half of its 5,000-member tax team uses proprietary AI platforms in daily work, while at EY India, more than 75% of its 6,500 tax professionals regularly use AI tools in their day-to-day work."We have already crossed over 1.3 million queries on the system this year," said Bhavin Shah, partner, Price Waterhouse & Co. "The scale at which tax professionals are using AI internally is significant, and we are seeing query volumes grow nearly 30% every 45 days."In the last 12 months, all the top firms have been working feverishly on building tightly controlled AI ecosystems trained on years of proprietary tax knowledge, past opinions and top legal databases, while trying to weave them in daily workflows of tax consultants on both compliance and advisory side of business."Generative AI is probabilistic, while tax is fundamentally deterministic," said Sameer Gupta, tax leader, EY India. "Clients ultimately need a precise answer on tax liability, merger structures or litigation positions. We have to bridge that gap."Experts say few markets offer a better test case for AI in tax than India. It is a market where tax has large transaction volumes, frequent regulatory updates and lots of litigation, making it a function that involves not only large amounts of data but is also heavily dependent on interpretation."In India, one transaction can simultaneously trigger GST, customs, transfer pricing and capital gains implications," Gupta said. "You also need to understand how courts and tribunals may interpret a position. The challenge is not just understanding the facts, but reframing and refining them through the right questions." With AI, research that once took several days can now be completed in minutes or hours. Tax associates can generate more comprehensive first drafts, while partners spend more time studying interpretations, searching for identifying risks and applying judgment."AI is not replacing expertise; it is amplifying it. The combination of deep domain knowledge and AI-driven intelligence is enabling our consultants to deliver sharper insights, faster turnaround times and more tailored outcomes for clients," said Gokul Chaudhri, president, Tax, Deloitte South Asia.With AI deployment, the traditional consulting model of scaling revenue by adding junior staff for research, drafting and compliance work, a structure that has long been followed in the tax business as well, is starting to shift as AI automates large parts of that pyramid."The expectation now is to deliver significantly higher revenue growth without proportionate increases in headcount," Shah said. "The pyramid structure is already beginning to change."