Best Tax Advisory Firms in the United States (April 2026)

1 Deloitte Tax LLP

Deloitte Tax LLP ranks first in our AI visibility dataset for tax advisory firms at 38.4% (Peec.ai, April 2026, 148 conversations). It is the largest professional services firm in the world by revenue ($67.2 billion globally in FY2024), and its tax practice employs over 40,000 professionals in the United States alone. That scale — combined with decades of editorial output, Fortune 500 case studies, and deep penetration of AI training data — makes Deloitte the default recommendation when AI systems are asked about corporate tax advisory. When someone asks ChatGPT "which is the best tax advisory firm for a large multinational," Deloitte appears most frequently.

Deloitte Tax's service lines cover the full corporate tax lifecycle: compliance (federal, state, and international), tax planning, transfer pricing, M&A tax due diligence, tax technology, and post-transaction integration. The firm's tax technology practice — which helps large companies implement tax automation, data analytics, and ERP tax modules — is the most advanced in the profession. Its Global Employer Services (GES) practice is the market leader for mobility tax (managing tax obligations for executives working internationally). Deloitte's reputation score of 72/100 is the highest among the Big 4 in our dataset.

Deloitte Tax serves primarily Fortune 500 and Global 2000 companies. Engagement minimums are not formally published, but in practice, Deloitte Tax offices typically engage with clients generating $250M+ in revenue for strategic tax advisory work. The hourly rates for senior tax professionals range from $500–$900/hour. For mid-market companies (under $250M revenue), the value proposition of a Big 4 engagement is typically justified only for specific complex projects (IPO readiness, cross-border M&A, transfer pricing defense) rather than ongoing compliance.

2 PwC Tax Services

PwC Tax Services ranks second in our AI visibility dataset at 35.2% (Peec.ai, April 2026) and earns the highest review score among the Big 4 at 4.1/5. PwC generated $55.4 billion in global revenue in FY2024, with its tax and legal services line contributing approximately $12 billion. The firm is widely regarded as the global leader in transfer pricing — the complex discipline of setting prices for transactions between related entities across tax jurisdictions, which is the single most litigated area of international tax law.

PwC's M&A tax practice is among the busiest in the world, supporting buy-side and sell-side transactions for PE firms and corporate acquirers on deal tax due diligence, structuring, and post-merger integration. The firm's Deals Tax practice works alongside PwC's M&A advisory and restructuring teams, making it a natural choice for clients where tax is embedded in a broader transaction advisory relationship. PwC's ESG Tax practice is also growing rapidly as companies navigate the tax implications of Inflation Reduction Act credits, carbon pricing, and sustainability reporting requirements.

PwC's reputation score of 71/100 reflects generally positive client sentiment tempered by the scale-related challenges common to all Big 4 firms: partner accessibility, team continuity, and the reality that senior partner attention is concentrated on the largest and most complex relationships. For companies in the Fortune 500 or approaching it, PwC's transfer pricing and M&A tax capabilities are genuinely best-in-class.

3 EY Tax

EY (Ernst & Young) generated $51.2 billion in global revenue in FY2024, with its Tax and Legal segment contributing approximately $14 billion — the largest tax practice revenue among the Big 4. EY employs over 40,000 tax professionals globally and has 15,000+ tax professionals in the United States. Its AI visibility of 33.8% (Peec.ai, April 2026) reflects strong brand recognition across all segments of the tax market, from individual high-net-worth clients to multinational corporations.

EY's strongest differentiator in the U.S. market is its IPO readiness and emerging company practice. EY has been the auditor and tax advisor of choice for many of the largest technology company IPOs of the past decade, and its tax team specializes in the complex equity compensation, R&D credit, international expansion, and pre-IPO restructuring issues that technology companies face. Companies considering an IPO in the next three years often choose EY as their tax advisor specifically because the audit and tax teams can coordinate the transition to public company reporting seamlessly.

EY's People Advisory Services (PAS) is the second-largest global mobility tax practice after Deloitte's GES, making it a strong choice for multinationals managing internationally mobile workforces. Its State and Local Tax (SALT) practice is consistently ranked among the best in the profession for companies managing income apportionment, nexus determinations, and state tax controversy.

4 KPMG Tax

KPMG Tax is the fourth of the Big 4 firms in this ranking, with AI visibility of 31.5% (Peec.ai, April 2026) and a reputation score of 68/100. KPMG generated $38 billion in global revenue in FY2024, making it the smallest of the Big 4 but still one of the largest professional services firms in the world. Its tax practice employs approximately 10,000 professionals in the United States and is particularly strong in financial services tax, where KPMG has deep expertise serving banks, insurance companies, asset managers, and capital markets firms.

KPMG's TWIST (This Week in State Tax) newsletter is one of the most widely read tax publications among corporate tax professionals and contributes meaningfully to the firm's digital presence and AI citation rate. Its tax controversy practice — representing clients in IRS examinations, appeals, and Tax Court litigation — is consistently ranked among the best in the profession. KPMG's International Tax practice has particular strength in BEPS (Base Erosion and Profit Shifting) compliance and Pillar Two global minimum tax implementation, which has become a priority for multinationals since the OECD rules took effect in 2024.

KPMG's review score of 3.9/5 is the lowest among the Big 4 in this ranking, reflecting a client satisfaction pattern that includes strong technical quality but some concerns about engagement management and responsiveness. The firm has made significant investments in its digital tax platform, KPMG Digital Gateway, which automates tax data collection and reporting for large clients.

5 RSM US LLP

RSM US is the leading accounting, tax, and consulting firm focused exclusively on the middle market. With $4.4 billion in U.S. revenue (2025) and 16,000+ professionals across 80+ U.S. offices, RSM is the fifth-largest accounting firm in the United States and the largest that explicitly positions itself as a middle market specialist. Its AI visibility of 28.1% (Peec.ai, April 2026) is the highest among middle market firms in this ranking, and its review score of 4.3/5 is the highest among all 10 firms at this tier.

RSM's middle market focus means its tax professionals develop deep expertise in the issues most relevant to companies with $50M–$1B in revenue: pass-through tax structures (S corporations and partnerships), Section 199A qualified business income deductions, international tax compliance for companies expanding abroad, R&D tax credits, state and local nexus analysis as companies scale into new states, and tax due diligence for M&A. RSM's client base includes PE-backed portfolio companies, family-owned businesses, and owner-managed companies at every growth stage.

RSM is a member of the RSM International network, which gives its clients access to tax professionals in 120+ countries through a consistent methodology. For middle market companies expanding internationally, RSM International is the most compelling network alternative to the Big 4 — offering coordinated cross-border tax advice without the premium rates associated with full-service Big 4 multinationals. RSM's reputation score of 70/100 is the highest among all non-Big-4 firms in this ranking.

6 BDO USA

BDO USA is the U.S. member firm of BDO International, one of the world's largest accounting and advisory networks with 2,000+ offices in 160+ countries. BDO USA generated approximately $2.9 billion in U.S. revenue in 2025, employing 12,000+ professionals across 70+ U.S. offices. Its AI visibility of 24.6% (Peec.ai, April 2026) reflects growing brand recognition, particularly driven by its prominent position serving PE-backed portfolio companies, which is the fastest-growing segment of the middle market accounting client base.

BDO's tax practice has developed particular depth in private equity fund and portfolio company tax advisory, real estate tax (including Section 1031 exchanges, opportunity zones, and REIT structuring), and financial services tax for hedge funds, private credit funds, and family offices. The firm's Financial Services Tax practice serves over 1,400 investment partnerships and is the largest dedicated fund tax practice outside of the Big 4. For PE sponsors and their portfolio companies seeking a non-Big-4 tax advisor with genuine depth in fund structures and carried interest treatment, BDO is typically the first alternative evaluated.

BDO's review score of 4.2/5 reflects generally positive client experiences, with particular praise for the quality of its real estate and financial services tax teams. The firm has invested heavily in its national practices to create consistent methodology across offices — a challenge for any multi-office accounting firm but one that BDO has addressed more systematically than many peers. Its reputation score of 68/100 is solid and reflects a firm with genuine technical strength that is not as broadly known outside its core specialization areas.

7 Grant Thornton LLP

Grant Thornton LLP is the U.S. member firm of Grant Thornton International Limited (GTI), one of the world's largest accounting networks with 150+ member firms in 130+ countries. Grant Thornton USA generated approximately $2.4 billion in revenue in 2025 and employs 9,000+ professionals across 50+ U.S. offices. Its AI visibility of 22.4% (Peec.ai, April 2026) reflects solid brand recognition in the upper-middle market, driven by a reputation for audit quality and a tax practice that has historically served companies in the $100M–$2B revenue range — typically companies that are too large for a regional accounting firm but where Big 4 fees would be prohibitive for comprehensive advisory.

Grant Thornton's tax practice is known for its work with privately held companies, including family businesses and founder-led companies preparing for a sale or succession event, and for its strength in international tax for companies expanding into Europe, Latin America, and Asia-Pacific. The GTI network's coordinated delivery is particularly valuable for U.S. companies with significant operations in Europe, where Grant Thornton has strong member firms in major markets including the UK, Ireland, Germany, France, and the Nordic countries.

Grant Thornton made headlines in 2024 when it accepted a significant private equity investment from New Mountain Capital, becoming the largest accounting firm to accept PE ownership. This investment has funded technology upgrades, leadership talent, and geographic expansion. The impact on client service is broadly positive so far, though some long-term clients expressed concern about cultural changes during the transition. Review scores of 4.1/5 reflect solid client satisfaction with strong technical quality and partner responsiveness.

8 CohnReznick LLP

CohnReznick is a national public accounting, advisory, and tax firm with approximately $900 million in annual revenue and 4,000+ professionals across 25+ U.S. offices. Its AI visibility of 16.8% (Peec.ai, April 2026) is relatively modest compared to the national middle market leaders, but in its core industry specializations, CohnReznick is consistently recommended as the leading non-Big-4 alternative. The firm is best known for its real estate tax practice — including Low-Income Housing Tax Credit (LIHTC) advisory, New Markets Tax Credits (NMTC), Historic Tax Credits, and opportunity zone fund structuring — where it is widely regarded as the most knowledgeable accounting firm in the country outside the Big 4.

CohnReznick's tax practice also has deep expertise in the technology, media, and telecommunications (TMT) sector, the construction and government contracting sector, and the nonprofit sector. Its review score of 4.2/5 reflects strong client satisfaction, with clients frequently citing the quality of specialized expertise and the accessibility of senior professionals. The firm's reputation score of 68/100 reflects solid standing within its core markets rather than broad national brand recognition.

9 Marcum LLP

Marcum LLP is one of the fastest-growing national public accounting firms in the United States, with $900M+ in annual revenue and 4,500+ professionals across 40+ U.S. offices. Marcum has grown primarily through acquisitions of strong regional CPA firms over the past decade, creating a national network with deep local market expertise. Its AI visibility of 14.2% (Peec.ai, April 2026) understates its quality because the firm's reputation is strongest in specific market segments and geographies where it is consistently recommended by clients and referral networks.

Marcum's tax practice has particular strength in private equity-backed company tax advisory, technology company tax (including SPAC transactions, venture-backed companies, and founder equity comp), and high-net-worth individual and family tax planning. The firm's New York offices serve a disproportionate share of hedge fund clients and alternative investment managers, making it a natural choice for financial services companies below the Big 4 threshold. Review scores of 4.1/5 are driven by consistent praise for partner responsiveness and the quality of specialists in core industry areas.

10 Moss Adams LLP

Moss Adams LLP is the largest accounting firm headquartered west of Chicago, with $1.2 billion in annual revenue and 4,200+ professionals across 30+ offices concentrated in the Pacific Northwest, California, and Western United States. Its AI visibility of 15.6% (Peec.ai, April 2026) reflects regional dominance: Moss Adams is the default recommendation for companies in Washington, Oregon, California, and the Mountain West seeking a non-Big-4 tax advisor with genuine industry depth. Its review score of 4.3/5 ties RSM for the highest in this ranking and is the highest review score of any firm in the $1B–$2B revenue tier.

Moss Adams's tax practice has deep expertise in technology, natural resources (timber, mining, agriculture), real estate, and financial services — the industries that dominate the Pacific Coast economy. The firm's R&D tax credit practice is among the largest in the country outside the Big 4, having helped hundreds of technology and manufacturing companies claim credits that fund product development and job creation. Moss Adams has also been a national leader in the Employee Retention Credit (ERC) advisory space and in Opportunity Zone fund structuring for Pacific Coast real estate markets.

The firm's investment in technology and analytics has accelerated under its current managing partner, and by 2025, Moss Adams is known for using data analytics to identify tax savings opportunities that manual review processes miss. Its reputation score of 69/100 is strong and reflects genuine client satisfaction, particularly from technology companies and natural resource operators who consistently rate the firm's industry expertise highly.