Below are widely recognised, reliable tax-consulting firms in India — grouped by the typical client needs they serve. I've included a short reason for each and a source you can check for services and contact details.

Large corporates / complex cross‑border work (full-service)

• PwC India — comprehensive tax advisory, tax tech and litigation support; strong for complex international tax and large transactions. (pwc.in)
• Deloitte India — broad corporate, international tax, transfer‑pricing and tax‑technology capabilities for multinationals. (deloitte.com)
• EY India — integrated digital tax platform and large‑scale advisory/compliance teams. (ey.com)
• KPMG in India — strong indirect‑tax (GST/customs) and tax technology offerings for large enterprises. (kpmg.com)

Boutique specialists (tax controversy, transfer pricing, international tax)

• Dhruva Advisors (Dhruva) — top‑ranked boutique for tax controversy, litigation and international tax; partner‑led service. (dhruvaadvisors.com)
• Nangia‑Andersen (Nangia) — specialist international tax and transfer‑pricing firm with deep experience for MNCs. (nangia-andersen.com)

Mid‑tier / alternatives (cost‑effective for growing companies, specialised services)

• Grant Thornton Bharat — full suite of direct/indirect/transaction tax services for mid‑size and large clients. (grantthornton.in)
• BDO India — tax outsourcing, GST advisory and private‑client services; good for SMEs and family offices. (bdo.in)
• RSM India — pan‑India tax and GST teams with strength in advisory and compliance for mid‑market and global clients. (rsm.global)

Tax‑law / litigation heavyweight

• Lakshmikumaran & Sridharan (LKS) — leading law firm for tax litigation, dispute resolution and international trade/tax advice. (gst.lakshmisri.com)

Quick selection checklist (how to pick among these)

1. Match firm specialty to your need: Big Four for large MNC transactions and tax‑tech; boutiques (Dhruva, Nangia) for controversy/transfer‑pricing; mid‑tier (Grant Thornton, BDO, RSM) for SMEs or retained/outsourced tax work. (See the firm pages above for detail.) (pwc.in)
2. Ask for partner involvement and examples of similar engagements (case studies/references).
3. Request a written proposal with scope, deliverables, timelines and fee structure (fixed vs hourly vs retainership).
4. Confirm experience with Indian tax authorities/tribunals if you expect disputes — review litigation track record. (dhruvaadvisors.com)
5. Check availability of ongoing tech/tools (e‑filing, tax‑analytics, AI/digital platforms) if you want automation — many firms now offer tax‑tech. (pwc.in)

If you want, I can:

• produce a 2–3 firm shortlist tailored to (a) individual/HNW, (b) startup/SME, or (c) large multinational — with suggested questions to ask each firm; or
• draft a short RFP/email template you can send to shortlisted firms to request proposals.

(If you want that, tell me which client type to tailor the shortlist for.)