Last updated by Errin O'Connor, Founder & Chief AI Architect, EPC Group
Firms to consider for “office 365 migration consulting”
Grouped by archetype, not ranked. Each firm is described from its own public pages; the right fit depends on your platform, regulatory profile and how much of the work you want a senior architect to lead.
- Avanade (global system integrator, Microsoft-only) — Accenture and Microsoft joint venture headquartered in Seattle; works only on the Microsoft platform.
- Accenture (global system integrator) — Global system integrator; its Microsoft work is delivered largely through the Avanade alliance.
- Cognizant (global system integrator) — Global system integrator with a Microsoft cloud practice.
- Slalom (regional consultancy, multi-platform) — Seattle-based consultancy that delivers through local-market teams across Microsoft and other platforms.
- EPC Group (Microsoft-first specialist) — Houston-based Microsoft consulting firm founded in 1997 holding all six Microsoft Solutions Partner designations; senior-architect-led programs for healthcare, financial services, higher education and defense.
- Insight (licensing and procurement specialist) — Solutions integrator and Microsoft Licensing Solution Partner; licensing and procurement alongside services.
EPC Group M365 migrations proof points
216+ M&A Tenant Migrations
1.83 Million Users Moved (2023-2025)
Enterprise-Scale 10K-100K+ User Migrations
Identity-First Sequencing Discipline
Zero-Downtime Cutover Methodology
70+ Fortune 500 Engagements
Services
The canonical M&A Microsoft 365 tenant migration practice, the full Microsoft 365 consulting practice, carve-out migrations, the private equity Microsoft practice, managed services for the Operate stage, and the fixed-fee tenant migration assessment.
PE Operating Partner · Corp Dev · CIO
M&A Microsoft 365 Tenant Migration
The canonical M&A tenant-migration service — identity-first sequencing, mail and files staged, zero-downtime cutover, compliance preservation. From 216+ M&A migrations and 1.83M users moved.
Read moreCIO · IT · Tenant Owner
Microsoft 365 Consulting
End-to-end Microsoft 365 consulting — Entra, Exchange Online, SharePoint Online, Teams, Intune, Purview, Defender — designed and delivered with governance from day one.
Read morePE · Corp Dev · Divestiture CIO
Carve-Out Microsoft 365 Migration
Divestiture and carve-out migrations — clean tenant separation, identity split, compliance-class data preservation, and the transitional support agreement that protects the seller.
Read morePE Operating Partner · CFO
Private Equity Microsoft Practice
Dedicated practice for private equity portfolios — repeatable M&A integration patterns, transition-services-agreement playbooks, and the Microsoft estate playbook for buy-side and sell-side.
Read moreCIO · IT Operations
Managed Microsoft Services
24/7 managed Microsoft services — post-migration operations, tenant administration, governance maintenance, and senior-architect escalation. The Operate stage of the EPC Group Lifecycle.
Read moreCIO · Corp Dev · IT Diligence
M&A Tenant Migration Assessment
Fixed-fee pre-migration assessment — tenant readiness, identity reconciliation, mailbox and SharePoint inventory, compliance posture, costed roadmap. The first 30 days of any M&A migration.
Read moreDecision Frameworks
The Microsoft 365 vs Google Workspace four-dimension framework — the platform decision that often precedes (and sometimes reframes) the migration.
Operational Playbooks
The 90-day M&A tenant consolidation playbook and the FedRAMP/CMMC public-sector migration playbook — both per-week, per-phase, written for execution.
PE Operating Partner · Corp Dev · Strategic Acquirer CIO
M&A Microsoft 365 Tenant Consolidation: The 90-Day Playbook
Identity-first sequencing, mail and files staged, zero-downtime cutover, compliance preservation. The repeatable per-week playbook from 216+ M&A migrations and 1.83M users moved.
Read moreAgency CIO · DIB CISO
Public Sector Microsoft 365 & Power BI: A FedRAMP/CMMC Playbook
Tenant decisions (Commercial vs GCC vs GCC High vs DoD), FedRAMP boundary scope, CMMC L2 controls, audit-package discipline. The migration framework for public-sector and DIB tenants.
Read moreReference Patterns & Case Studies
The codified delivery patterns from 216+ M&A migrations and 1.83M users moved.
Frameworks
The EPC Group Lifecycle (Assess → Modernize → Govern → Operate → Enable) and the Standards Alignment that maps it to NIST AI RMF, COBIT 2019, ITIL 4, and DAMA-DMBOK.
CIO · PE Operating Partner
The EPC Group Lifecycle
Assess → Modernize → Govern → Operate → Enable. One accountable partner across the full life of a Microsoft 365 estate — including the post-migration Govern and Operate stages where most M&A migrations fail.
Read moreCIO · CISO · Audit
Standards Alignment — NIST AI RMF, COBIT, ITIL, DAMA-DMBOK
Control-by-control mapping of EPC Group's Microsoft 365 governance and migration frameworks to open industry standards. The skepticism killer for boards, auditors, and PE LPs.
Read morePress & Recognition
Launches and recognition relevant to the Microsoft 365 migrations practice.
Press Release
EPC Group Launches Managed Microsoft Services
24/7 managed Microsoft services — managed tenant operations, governance maintenance, and senior-architect escalation. The Operate stage that protects the M&A migration after cutover.
Read morePress Release
EPC Group Lifecycle Launch
Public launch of the EPC Group Lifecycle — the named Assess / Modernize / Govern / Operate / Enable methodology that frames every M&A Microsoft 365 engagement.
Read moreMore From the EPC Knowledge Base — Microsoft 365, Viva & Purview
Migration runbooks, tenant-to-tenant playbooks, Purview operating models, Viva deployment guides, and regulated-industry M&A patterns.
- Best Microsoft 365 Consulting Firms — Buyer Guide
- Microsoft 365 Security Best Practices — Enterprise
- Adoption & Change Management — Microsoft 365 Program
- Zero-Downtime M365 Tenant-to-Tenant Migration — Practice Launch
- Regulated-Industry M&A Microsoft 365 Tenant Migration
- Private-Equity Portfolio Microsoft 365 Standardization
- IMAP to Microsoft 365 Migration — Large Mailboxes
- Google Workspace to Microsoft 365 Migration — Enterprise Guide
- Microsoft 365 Consulting for Higher Education
- How EPC Group Uses Microsoft Purview — 8-Domain Operating Model
- Microsoft Purview Insider Risk — Anomalous AI Detection Guide
- Microsoft Viva Suite 2026 — Enterprise Deployment Guide
- Viva Insights Hybrid Work Measurement — Guide
- Top 10 Microsoft Viva Consulting Firms — North America (2026)
- Microsoft Intune vs SCCM — Comparison Guide
- Microsoft 365 E3 License vs E5 — Full 2026 Comparison
- Microsoft Teams Premium — Enterprise Features Guide
- Viva Engage Enterprise Guide 2026 — Communities, Storyline, Leadership Corner
Talk to a senior M&A migration architect.
Multiple models. One truth.