Company lists · Data refreshed September 2026

Top 25 Tax processing outsourcing companies worldwide

Name: Tax processing outsourcing companies worldwide
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 29, 2026 9,076 companies tracked

RevenueBase identified 9,076 tax processing outsourcing companies worldwide as of September 2026 and tracks 124,050 professional contacts across them, including 22,620 with verified work emails. The United States is the largest market and Sao Paulo the largest hub.

This list covers tax processing outsourcing companies worldwide, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 29, 2026. Country and city lists for tax processing outsourcing companies follow the table.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 29, 2026 86% judged on-target in blind review

9,076Companies

124,050Contacts tracked

22,620Verified emails

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The 25 largest tax processing outsourcing companies worldwide

Ranked by team size

Top 25 of 9,076 tax processing outsourcing companies worldwide, ranked by team size, largest first. Data refreshed Sep 29, 2026. RevenueBase Smart Search rates how each company's information relates to tax processing outsourcing companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	H&r Block	Indirect evidence	Kansas City, MO, United StatesHQ checked Sep 29, 2026	10001+	59,451 contacts →
	Indirect evidence “H&R Block’s purpose is simple: To provide help and inspire confidence in our clients and communities everywhere.” Source: RevenueBase Database · checked Sep 29, 2026
2	RYAN	Partial evidence	Dallas, TX, United StatesHQ checked Sep 29, 2026	5,001-10,000	6,089 contacts →
	Partial evidence “Ryan, an award-winning global tax services and software provider, is the largest Firm in the world dedicated exclusively to business taxes.” Source: RevenueBase Database · checked Sep 29, 2026
3	D&v Philippines	Partial evidence	Makati, PhilippinesHQ checked Sep 29, 2026	1,001-5,000	1,021 contacts →
	Partial evidence “D&V Philippines is a finance and accounting outsourcing company that helps CFOs, accounting firms, audit firms, and other professional services firms build reliable offshore…” Source: RevenueBase Database · checked Sep 29, 2026
4	KMK	Partial evidence	Ahmedabad, IndiaHQ checked Sep 29, 2026	1,001-5,000	628 contacts →
	Partial evidence “KMK Ventures is a leading Outsourced Accounting & Tax solutions company providing services to clients based out of USA.” Source: RevenueBase Database · checked Sep 29, 2026
5	Drake Software	Partial evidence	Franklin, United StatesHQ checked Sep 29, 2026	501-1,000	561 contacts →
	Partial evidence “Drake Software, a private company founded in 1977, provides software solutions to over tax and accounting firms that file more than 40 million tax returns every year.” Source: RevenueBase Database · checked Sep 29, 2026
6	Outbooks	Partial evidence	Harrow, United KingdomHQ checked Sep 29, 2026	201-500	477 contacts →
	Partial evidence “Outbooks is a leading provider of outsourcing services to accounting and bookkeeping firms.” Source: RevenueBase Database · checked Sep 29, 2026
7	Global FPO	Strong evidence	Noida, IndiaHQ checked Sep 29, 2026	501-1,000	474 contacts →
	Strong evidence “Global FPO is an Accounting, Bookkeeping and Tax Consulting, and outsourcing company that helps CPAs, accounting firms, small and mid-sized businesses, and startups strengthen…” Source: RevenueBase Database · checked Sep 29, 2026
8	Gestión Tributaria Territorial	Indirect evidence	Alicante, SpainHQ checked Sep 29, 2026	501-1,000	395 contacts →
	Indirect evidence “grupo gtt es una empresa tecnológica especializada en la gestión de tributos.” Source: RevenueBase Database · checked Sep 29, 2026
9	Cohesive	Indirect evidence	Exton, PA, United StatesHQ checked Sep 29, 2026	501-1,000	364 contacts →
	Indirect evidence “Cohesive is a leading solutions provider and systems integrator for IBM Maximo.” Source: RevenueBase Database · checked Sep 29, 2026
10	Advantage ONE TAX Consulting	Partial evidence	Sterling, VA, United StatesHQ checked Sep 29, 2026	201-500	347 contacts →
	Partial evidence “Advantage One Tax Consulting is a multi-disciplinary group of highly experienced tax professionals who understand the tax practice in its true spirit, examine the issues it faces…” Source: RevenueBase Database · checked Sep 29, 2026
11	Process Solutions	Partial evidence	Budapest, HungaryHQ checked Sep 29, 2026	201-500	328 contacts →
	Partial evidence “Process Solutions (PS) is a group providing Business Process Outsourcing services, operating an independent accounting business in the Central European region.” Source: RevenueBase Database · checked Sep 29, 2026
12	Unison Globus	Partial evidence	Coral Springs, FL, United StatesHQ checked Sep 29, 2026	201-500	320 contacts →
	Partial evidence “Unison Globus is a global accounting outsourcing and offshore staffing partner dedicated to supporting CPA firms and accounting professionals.” Source: RevenueBase Database · checked Sep 29, 2026
13	GI Outsourcing	Partial evidence	London, United KingdomHQ checked Sep 29, 2026	201-500	311 contacts →
	Partial evidence “GI Outsourcing is a UK-based accountants outsourcing firm.” Source: RevenueBase Database · checked Sep 29, 2026
14	Buchprufer Consultants LLP	Partial evidence	Calicut, IndiaHQ checked Sep 29, 2026	201-500	294 contacts →
	Partial evidence “Founded in 2007, Buchprufer Consultants has grown into a trusted and reputed outsourcing partner delivering high-quality financial and professional services.” Source: RevenueBase Database · checked Sep 29, 2026
15	Taxprime	Partial evidence	Jakarta Selatan, IndonesiaHQ checked Sep 29, 2026	201-500	269 contacts →
	Partial evidence “TaxPrime is a Tax Consulting Firm, based in Jakarta, the Capital City of Indonesia.” Source: RevenueBase Database · checked Sep 29, 2026
16	Mayatax	Indirect evidence	Houston, TX, United StatesHQ checked Sep 29, 2026	501-1,000	269 contacts →
	Indirect evidence “Growth exposes financial weakness.” Source: RevenueBase Database · checked Sep 29, 2026
17	FBC Farm And Small Business TAX Consultants	Indirect evidence	Calgary, AB, CanadaHQ checked Sep 29, 2026	201-500	260 contacts →
	Indirect evidence “For more than 70 years, our focus has always been to bring financial peace of mind to our Canadian business owners.” Source: RevenueBase Database · checked Sep 29, 2026
18	Mercurius Advisory Services	Indirect evidence	New Delhi, IndiaHQ checked Sep 29, 2026	201-500	249 contacts →
	Indirect evidence “Mercurius Advisory Services (MAS) provides comprehensive suite of accounting, bookkeeping and taxation services to small, medium and large enterprises.” Source: RevenueBase Database · checked Sep 29, 2026
19	Bravo Simplify Everything	Indirect evidence	Sao Paulo, BrazilHQ checked Sep 29, 2026	51-200	240 contacts →
	Indirect evidence “Somos uma empresa especialista em soluções fiscais com grande portfólio de serviços para sua área fiscal e tributária, o que nos permite cuidar de todas as etapas da sua…” Source: RevenueBase Database · checked Sep 29, 2026
20	SNI	Partial evidence	Istanbul, TürkiyeHQ checked Sep 29, 2026	51-200	240 contacts →
	Partial evidence “SNI is a Computer Technology Corporation providing Tax Compliance and Regulatory Reporting softwares, interfaces and technologies around the world.” Source: RevenueBase Database · checked Sep 29, 2026
21	Synergi	Strong evidence	Florence, SC, United StatesHQ checked Sep 29, 2026	201-500	214 contacts →
	Strong evidence “Synergi specializes in processing federal and state tax credits for employers across the United States and Puerto Rico.” Source: RevenueBase Database · checked Sep 29, 2026
22	Zenwork, INC	Partial evidence	Fayetteville, AR, United StatesHQ checked Sep 29, 2026	51-200	206 contacts →
	Partial evidence “Zenwork, through its Tax1099 and Compliancely brands, is a fast-growing digital tax compliance and regulatory reporting technology company, with 10+ years of experience powering…” Source: RevenueBase Database · checked Sep 29, 2026
23	Systax	Partial evidence	São Paulo, BrazilHQ checked Sep 29, 2026	51-200	189 contacts →
	Partial evidence “Systax: The Evolution of Tax Intelligence.” Source: RevenueBase Database · checked Sep 29, 2026
24	Assessor-Bordin Consultores Empresariais SS	Strong evidence	São Paulo, BrazilHQ checked Sep 29, 2026	51-200	177 contacts →
	Strong evidence “ABordin has provided high-quality services in the following areas, for the past 37 years: Business Process Outsourcing, Audit and Tax Consulting, Individual Income Tax…” Source: RevenueBase Database · checked Sep 29, 2026
25	Wolters Kluwer, TAA North America US Small Firms	Partial evidence	United StatesHQ checked Sep 29, 2026	10001+	174 contacts →
	Partial evidence “Wolters Kluwer, TAA North America US Small Firms is part of Wolters Kluwer Tax & Accounting.” Source: RevenueBase Database · checked Sep 29, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: tax processing outsourcing companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names tax processing outsourcing companies.
Partial evidence: Its own public description names part of tax processing outsourcing companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name tax processing outsourcing companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 9,076 tax processing outsourcing companies worldwide

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Tax processing outsourcing companies worldwide at a glance

As of Sep 29, 2026

18.2%Verified-email coverage

13.7Average contacts per company

1-10Median size (employees)

1.5%Largest-city concentration · Sao Paulo

Sep 29, 2026Page data refreshed

Companies by employee count

1-10

6,277

11-50

2,192

51-200

365

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency is reported on each country list linked below.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among tax processing outsourcing companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
Coverage: Every country. Country and city lists for tax processing outsourcing companies are linked below.
What qualifies: Companies worldwide whose own description of what they do matches “tax processing outsourcing companies”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names tax processing outsourcing companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among tax processing outsourcing companies, and records with no verified work email.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 22,620 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 29, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Tax processing outsourcing companies by location

29 lists · largest first

Every Tax processing outsourcing companies list RevenueBase publishes, by country and city. Counts are matching companies in each list as of its own refresh date.

Countries

Cities

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names tax processing outsourcing companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many tax processing outsourcing companies are there worldwide?

RevenueBase identified 9,076 tax processing outsourcing companies worldwide as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

H&r Block, headquartered in Kansas City, tops this list with the largest team on record.

Which country has the most tax processing outsourcing companies?

The United States leads with 3,818 companies, followed by Germany (698) and India (597). Every tax processing outsourcing companies list by country and city is linked on this page.

Which city has the most tax processing outsourcing companies?

Sao Paulo leads with 137 headquartered companies, followed by Houston (95) and New York (90).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 22,620 verified decision-maker contacts tracked across these 9,076 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 29, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.