SharePoint Online Migration Enterprise Playbook (2026)

SharePoint Online Migration Enterprise Playbook (2026)

Updated: April 25, 2026 · By: Errin O'Connor, Founder & Chief AI Architect, EPC Group · Reading time: 23 min

SharePoint 2016 / 2019 end-of-support is driving the largest SharePoint migration wave since 2013. EPC Group has migrated 6,500+ SharePoint sites; this is the 24-week Fortune 500 playbook.

Why migrate now

• SharePoint 2016 mainstream support ended; extended ends 2026-07-14.
• SharePoint 2019 mainstream ended 2024-01; extended 2026-07-14.
• SharePoint Subscription Edition is the only on-prem path forward.
• Microsoft Copilot for SharePoint requires SharePoint Online.
• Cost of running on-prem (servers + SQL + admin labor) typically exceeds SharePoint Online for 5,000+ user environments.

The 24-week migration plan

Phase 1: Discovery + Assessment (weeks 1-4)

• Site inventory (typical Fortune 500: 800-3,000 sites).
• Permission analysis.
• Custom solution inventory (workflows, web parts, add-ins).
• Content gravity analysis (size, version count, files).
• Compliance / sensitivity classification.

Phase 2: Information Architecture Redesign (weeks 4-8)

• Hub-and-spoke vs flat IA decision.
• Site collection consolidation.
• Modern site templates.
• Permission group rationalization.
• Sensitivity label taxonomy.

Phase 3: Identity + Network Prep (weeks 6-10)

• Microsoft Entra ID Connect health check.
• Entra ID groups for SharePoint permissions.
• Conditional Access policies.
• Network throughput sizing.
• ExpressRoute (if applicable).

Phase 4: Governance Framework (weeks 8-12)

• Governance committee.
• Site provisioning template.
• Approval workflows.
• Lifecycle management.
• External sharing policy.

Phase 5: Pilot Migration (weeks 12-16)

• 50-100 sites migrated.
• Validate tooling + process.
• User feedback loops.
• Tool tuning.

Phase 6: Wave Migration (weeks 16-22)

• Migrate in waves of 100-300 sites.
• Monitor performance.
• Cutover communications.
• Issue resolution.

Phase 7: Decommission + Optimization (weeks 22-24)

• On-prem decommission plan.
• License rationalization.
• Modern UX adoption push.
• Power Platform integration.

Tooling

• ShareGate — best for governance + IA-aware migration.
• Quest On Demand Migration — best for very-large-scale (>1M items).
• Native PnP PowerShell — for custom scenarios + small migrations.
• Microsoft Migration Manager — free; OK for small files; struggles with custom workflows.

EPC Group default: ShareGate for 90% of Fortune 500 migrations.

8 risk mitigations

1. Permission audit before migration — fix oversharing pre-migration; saves 10-20× post-migration.
2. Custom solution remediation — InfoPath, classic workflows, custom code need replacements.
3. OneDrive content sweep — move OneDrive content that should be in Teams sites.
4. Email + Teams integration testing — Outlook attachments + Teams channel files.
5. External user re-credentialing — external users on classic sites need re-onboarding.
6. Versioning policy — set retention before migration to control storage cost.
7. Sensitivity labels first — apply labels before migration; carry through.
8. Hub navigation testing — modern hub navigation breaks if subsites aren't restructured.

Cost

For Fortune 500 (8,000+ users, 1,500-3,000 sites):

• EPC Group fixed-fee migration: $400-900K
• ShareGate licensing: $40-80K
• Internal labor: 4-8 FTEs × 6 months
• Microsoft 365 licensing impact: typically neutral (existing M365 users have SharePoint Online).
• Year 1 total: ~$1.5-2.5M

Frequently Asked Questions

How long does a SharePoint migration take?

24 weeks for Fortune 500. 12-16 weeks for mid-market. 4-8 weeks for SMB.

What about on-prem custom solutions?

Most need to be rewritten in modern Power Platform / SPFx. EPC Group's solution-modernization library has 50+ pre-built modern equivalents for common classic patterns.

Should we run hybrid SharePoint indefinitely?

No — hybrid SharePoint is for migration transitions, not steady state. Microsoft has been clear that all-cloud is the modern target. Hybrid mode introduces complexity that costs more than its limited benefits long-term.

What's the difference between SharePoint Online and SharePoint Subscription Edition?

SharePoint Online = SaaS, fully managed by Microsoft. SharePoint Subscription Edition = on-prem version with subscription licensing (replaces on-prem SharePoint 2016/2019). For 95% of enterprises, SharePoint Online is the right path.

Do we need to redesign IA?

Highly recommended. Migrating bad IA gets you bad-IA-in-the-cloud. Most Fortune 500 migrations use the migration as the IA redesign opportunity.

What about content over 10 years old?

EPC Group's archive-vs-migrate decision: content >7 years old with no access in last 18 months → archive to retention-only Storage account. Content 4-7 years → migrate but flag for retention review.

How do we handle workflows?

Classic SharePoint Designer workflows: rebuild in Power Automate. InfoPath: rebuild as Power Apps. Custom workflow code: SPFx web parts + Power Automate orchestration.

What's the most overlooked migration risk?

External user re-onboarding. Classic SharePoint external users won't auto-migrate; they need re-credentialing via Entra B2B. Plan dedicated communication + support.

Can users keep working during migration?

Yes — ShareGate's incremental sync allows continued use of source while target is being prepared. Cutover happens during off-hours per site.

What about Power BI integration with SharePoint?

Migrate Power BI reports embedded in SharePoint pages. Modern SharePoint has native Power BI web parts; classic embeds may need rebuilding.

Migrating to SharePoint Online? EPC Group has shipped 6,500+ SharePoint implementations. Schedule a migration assessment or explore SharePoint services.