SharePoint Migration Best Practices: The Enterprise Planning Guide for 2026

SharePoint Migration Best Practices: Enterprise Guide 2026

TL;DR: Enterprise SharePoint migration success depends on assessment quality, content cleanup, and permission restructuring — not just tool selection. EPC Group has completed 500+ migrations. Organizations that clean content before migrating reduce data volume by 40–50% and cut project timelines proportionally. Last updated: 2026. Read time: 7 min.

Key facts

• SharePoint Server 2016 reached end of support in July 2026. Organizations still on-premises face security risk.
• EPC Group has completed 500+ enterprise SharePoint migrations since 2001, from 100-user to 50,000-user projects.
• A 50 TB source environment typically reduces to 20–30 TB after content cleanup.
• Removing 25 TB of unnecessary content saves $5,000/month ($60,000/year) in SharePoint Online storage.
• Content cleanup alone reduces migration duration by 40–50%.
• Custom solution remediation accounts for 30–40% of total migration budget.

Why migrate to SharePoint Online in 2026?

SharePoint Server 2016 reached end of support in July 2026. SharePoint Server 2019 has entered extended support with limited security patches. Organizations running on-premises SharePoint face escalating costs and security vulnerabilities from unpatched systems.

They also lose access to modern Microsoft 365 capabilities. Copilot, Viva, and Loop require SharePoint Online. The business case for migration has never been stronger.

Key drivers for migration

• End of support: SharePoint 2016 end of support eliminates security patches. Running unsupported software creates unacceptable risk for regulated industries.
• Copilot readiness: Microsoft 365 Copilot only works with SharePoint Online content. Organizations that want AI for document summarization and search must migrate.
• Infrastructure cost elimination: On-premises requires SQL Server, Windows Server, hardware refresh, patching, backup, and skilled administrators. SharePoint Online eliminates all of these.
• Modern collaboration: SharePoint Online integrates with Teams, OneDrive, Loop, Viva, and Power Platform. On-premises cannot match this.
• Compliance capabilities: Microsoft Purview retention, sensitivity labels, DLP, and eDiscovery work natively with SharePoint Online. On-premises equivalents require separate infrastructure.

Migration assessment framework

The assessment is the most critical phase. Skipping it leads to scope surprises, permission failures, and content loss. EPC Group evaluates five dimensions across the source environment.

Dimension 1: Content inventory

• Total content volume (TB) across all site collections
• Number of site collections, sub-sites, lists, and libraries
• Files exceeding SharePoint Online limits (250 GB max file size, 400-character path length)
• Version history volume (often 3–5x the base content volume)
• Content age distribution (active, archive, stale)

Dimension 2: Permission complexity

• Number of unique permission scopes (broken inheritance points)
• Direct user permissions vs. group-based permissions
• Active Directory group nesting depth
• External sharing configuration and custom permission levels

Dimension 3: Customizations

• Farm solutions (WSP packages deployed to the farm)
• Sandbox solutions (may contain server-side code)
• InfoPath forms (forms services, browser-rendered forms)
• SharePoint Designer workflows (2010 and 2013 engines)
• Custom master pages and page layouts

Dimension 4: Integration dependencies

• Business applications reading/writing to SharePoint (ERPs, LOB systems)
• Automated workflows triggering external systems
• BI reports (Power BI, SSRS) connected to SharePoint lists
• Mapped network drives pointing to SharePoint document libraries

Dimension 5: User impact

• Total user count and geographic distribution
• Power users vs. casual users (affects adoption complexity)
• Critical business processes dependent on SharePoint
• Training requirements and change management readiness

Content audit and cleanup

Do not migrate everything. Organizations running SharePoint for 10–15 years typically accumulate 40–60% of content that is stale (not accessed in 3+ years), duplicated, or no longer relevant. Migrating this content wastes bandwidth, increases storage costs, and pollutes search results.

Content cleanup saves real money

A 50 TB source environment typically reduces to 20–30 TB after proper content cleanup. At SharePoint Online storage rates ($0.20/GB/month beyond the included quota), removing 25 TB saves $5,000/month — that is $60,000 per year.

Cleanup also reduces migration duration by 40–50%. This cuts both project timelines and consulting costs. It is the highest-ROI activity in any migration project.

Content classification framework

• Inventory and classify — use Microsoft Purview Data Lifecycle Management scan
• Duplicate detection — fingerprint-based identification
• Stale content identification — last-accessed date older than 3 years
• Owner outreach — automated emails to content owners for review
• Archive declared records — move to Microsoft Purview Records Management
• Delete candidates — disposition workflow for confirmed deletes

Migration tool selection

The tool landscape has consolidated around a few enterprise-grade options. Tool selection depends on source environment, volume, permission complexity, and budget.

• SPMT (free): Best for file share migrations under 100 TB. Throughput: 1–2 TB/day per agent for file shares; 500 GB–1 TB/day for SharePoint-to-SharePoint.
• ShareGate: Best for SharePoint-to-SharePoint under 20,000 users. Strong permission mapping and pre-migration reporting. Cost: ~$15,000/year.
• AvePoint FLY: Best for Fortune 500 with complex compliance requirements. Cloud-hosted, multi-geo, API-driven. Cost: ~$25,000/year and up.

Permission mapping and restructuring

Permission migration is the most technically challenging aspect. The source environment typically has years of ad-hoc assignments. Broken inheritance spans hundreds of levels. Direct user permissions do not translate cleanly to SharePoint Online.

EPC Group restructures permissions during migration rather than replicating the existing mess. This follows the principle of group-based permissions mapped to Entra ID security groups.

Permission restructuring approach

• Audit current state: Run permission reports across all site collections. Identify unique scopes, orphaned users, and direct user permissions.
• Design target model: Define a target model using Microsoft 365 groups and Entra ID security groups. Map business roles to permission levels.
• Create mapping table: Translate every source AD group and permission level to the target Entra ID group and SharePoint permission level.
• Validate with stakeholders: Review the mapping with site owners. Confirm no access gaps or over-provisioning.
• Test with pilot content: Migrate a representative subset. Verify access with test accounts across different permission levels.

Customization remediation

SharePoint Online does not support farm solutions, sandbox solutions with server-side code, or SharePoint Designer workflows. Every customization requires a decision: remediate, retire, or replace.

Remediation options:

• Convert InfoPath forms to Power Apps or SPFx web parts
• Replace SharePoint Designer workflows with Power Automate flows
• Rebuild server-side web parts as SPFx client-side web parts
• Replace timer jobs with Azure Functions or Power Automate scheduled flows

Budget 30–40% of total migration effort for customization remediation. EPC Group assesses all customizations in the discovery phase and provides remediation-or-retire recommendations for each one.

Cutover planning and execution

Cutover is the final phase where remaining delta content migrates, DNS records update, and users redirect to SharePoint Online. Minimizing the cutover window is critical for business continuity.

Cutover execution timeline

• Friday 6:00 PM — Set on-premises sites to read-only. Begin final delta migration pass.
• Friday 10:00 PM — Final delta completes. Run migration validation reports.
• Saturday 8:00 AM — Execute DNS changes and URL redirects.
• Saturday 12:00 PM — User acceptance testing with designated testers across all business units.
• Sunday 6:00 PM — Resolve identified issues. Finalize go/no-go for Monday.
• Monday 6:00 AM — Full production availability on SharePoint Online. Support team on standby.

Post-migration validation

Validation confirms that content, permissions, metadata, and functionality transferred successfully. EPC Group runs a structured validation checklist within 48 hours of cutover.

• Content integrity: Compare item counts at site collection, library, and folder level. Investigate any discrepancies.
• Permission verification: Test access with representative users. Verify owners, members, and visitors see the correct content.
• Search validation: Confirm SharePoint Online search returns migrated content. Verify managed property mappings.
• Workflow validation: Trigger all remediated workflows and verify end-to-end execution.
• Compliance features: Confirm retention policies, sensitivity labels, and DLP apply to migrated content.

Frequently asked questions

How long does an enterprise SharePoint migration take?

Enterprise migrations typically take 3–12 months. A 5,000-user organization with 10 TB of content averages 4–6 months (1 month assessment, 1 month architecture, 1–2 months pilot, 1–2 months production waves).

Organizations with 25,000+ users and 100+ TB require 8–12 months. Common delays: content cleanup, permission restructuring, and custom solution remediation.

What is the best SharePoint migration tool?

It depends on scope. EPC Group recommends ShareGate as the primary tool for complex SharePoint-to-SharePoint migrations under 50 TB.

For very large-scale migrations (50+ TB), SPMT combined with Migration Manager gives free, high-throughput bulk migration. AvePoint is the best choice for organizations with complex compliance requirements like HIPAA or FedRAMP.

How do I handle permissions during migration?

Start with a permission audit. Identify unique permissions, broken inheritance, and direct user permissions. Restructure in the target environment using SharePoint groups mapped to Entra ID security groups.

Never migrate broken inheritance or user-level permissions. Both ShareGate and SPMT support permission mapping tables that translate source groups to target groups during migration.

Should I migrate SharePoint Server customizations to SharePoint Online?

Do not migrate server-side customizations directly. SharePoint Online does not support farm solutions, sandbox solutions with code, or server-side deployments. Remediation options include Power Apps for forms, Power Automate for workflows, and SPFx web parts for custom UI components. Budget 30–40% of migration effort for this work.

What does enterprise SharePoint migration cost?

• Small (1,000 users, 2 TB): $50,000–$100,000
• Medium (5,000 users, 20 TB): $150,000–$300,000
• Large (25,000+ users, 100+ TB): $500,000–$1,500,000
• Tool licensing (ShareGate): $5,000–$25,000 additional
• EPC Group provides fixed-price proposals after the assessment phase

Start your SharePoint migration assessment

EPC Group has completed 500+ enterprise SharePoint migrations with zero data loss incidents. Call (888) 381-9725 or schedule a discovery call at /schedule to receive a migration scope estimate and tool recommendation.