LibreOffice vs Excel: What UK SMEs Need to Know Before Switching Their Templates

Thinking of dumping Microsoft 365 to save money? Read this first.

UK SMEs tell us the same things: reporting is time-consuming, templates are customised with complex formulas and macros, and staff expect files to work without surprises. Switching from Excel to LibreOffice can cut licence costs — but it can also break key workflows if you skip proper testing and conversion. This guide gives a pragmatic, step-by-step compatibility checklist for migrating templates, formulas and simple macros — plus testing methods and fallback options so your business keeps running while you migrate.

The 2026 context: why this decision matters now

As of early 2026 the commercial landscape for office suites changed in three ways that affect UK SMEs:

• Cost pressures and privacy concerns accelerated migration interest. After late-2025 updates to Microsoft licensing and renewed focus on data residency, many organisations re-examined open-source alternatives.
• LibreOffice development continued through 2024–25 with better formula compatibility and improved file import/export, but some advanced Excel features (Power Query, modern dynamic-array LAMBDA constructs, advanced VBA edge-cases) remain weak spots.
• Hybrid tool ecosystems became common: many SMEs adopt a mixed approach — LibreOffice for most users, Excel retained for legacy macros and heavy Power Query pipelines.

Quick verdict for UK SMEs

If your templates use basic formulas, tables, pivot tables and minimal VBA, a well-managed migration to LibreOffice can save licence fees while keeping workflows intact. If your templates rely on Power Query, advanced VBA that calls COM or external APIs, or Excel-only functions (eg. extensive use of LET/LAMBDA, some dynamic array trickery), plan a hybrid or staged migration and budget for conversion/customisation services.

Practical outcomes

• Simple templates: typically convert successfully with small edits.
• Moderately complex templates (nested formulas, user-defined functions, basic macros): expect manual adjustment and testing.
• Highly complex templates (Power Query, complex VBA/COM automation, Excel Add-ins): often require rewriting or keeping Excel for those workflows.

Pre-migration checklist: audit, prioritise, score

Start with an inventory. You can’t convert what you don’t know exists.

1. Catalogue every workbook: name, owner, business purpose, file path, last modified date, size.
2. Assign an impact score: how critical is this workbook to operations? (1–5)
3. Flag macro usage: open each .xlsm/.xls and note whether macros exist and approximate complexity (see Macro Complexity section below).
4. List feature use: Power Query, pivot tables, charts, data validation, conditional formatting, external data connections, add-ins.
5. Pick top 10 priority templates for a pilot migration — these should represent common workflows and pain points.

Formula compatibility: common pitfalls and fixes

Most spreadsheet formula incompatibilities fall into three categories: missing functions, differences in behaviour (eg. handling of arrays), and named ranges or table references.

Functions to check first

• XLOOKUP — widely used in modern Excel. If not supported in your LibreOffice version, replace with INDEX/MATCH for portability.
• Dynamic array functions (FILTER, UNIQUE, SEQUENCE, SORT) — LibreOffice has improved array handling, but complex spill behaviour can differ. Convert important dynamic formulas into helper columns or legacy array formulas where necessary.
• LET and LAMBDA — powerful in Excel but not reliably available in LibreOffice. Refactor reusable logic into helper cells or custom functions in LibreOffice Basic or Python.
• POWER QUERY / Get & Transform — not available in LibreOffice. Migrate ETL to external scripts (Python/PowerShell) or central data stores (CSV, database).

Practical formula conversion steps

1. Make a copy of the original .xlsx/.xlsm.
2. Open the copy in LibreOffice Calc and immediately save as .ods.
3. Scan for error indicators (#VALUE!, #NAME?, #N/A) and list affected cells.
4. Replace unsupported functions with portable equivalents (INDEX/MATCH for XLOOKUP, helper columns for dynamic arrays).
5. Check named ranges and structured table references – convert or simplify them if Calc can’t interpret them.
6. Recreate or simplify conditional formatting rules — complex multi-rule rulesets sometimes lose priority order.

Macro conversion: realistic expectations

Excel macros are usually VBA. LibreOffice supports LibreOffice Basic and has partial VBA compatibility. In practice, simple macros often import and run with minor edits; complex VBA that references Windows COM objects, Office-specific APIs, or uses Add-Ins tends to fail.

Macro complexity categories

• Low complexity: formatting macros, simple loops, MsgBox dialogs. High chance of import with minor editing.
• Medium complexity: file I/O, ranges manipulation, reliance on Excel object model. May require rewriting to LibreOffice Basic or Python with the UNO API.
• High complexity: COM automation, API calls to other Office products, integration with external add-ins. Best kept in Excel or fully rewritten.

Step-by-step macro conversion guidance

1. Export or copy the macro code from the Excel workbook (Tools > Macro > Visual Basic Editor in Excel).
2. Open the workbook in LibreOffice and access Tools > Macros > Organise Macros to view imported code (LibreOffice will attempt to import VBA into a Basic-equivalent module).
3. Run the macro and record errors. Note the failing lines and the API calls used (Excel objects like Application, Workbook, Worksheet, Range).
4. For small macros, perform simple edits (variable declarations, minor syntax changes). Test again.
5. For medium complexity, consider rewriting using LibreOffice Basic or Python and the UNO bridge. Use modular unit-testing where possible.
6. For high complexity, consider keeping that template on a Windows/Excel machine or converting the process to a server-side script that outputs a processed file.

Recommendation: treat macro conversion as a development task, not a checkbox. Allocate time for testing, code review and, where needed, a rewrite by a spreadsheet developer.

Testing framework: how to be confident before rollout

Adopt a reproducible test plan to compare Excel and LibreOffice outputs. Automate where you can.

1. Create a representative sample dataset with edge cases (empty values, long text, special characters, very large numbers).
2. Golden-run comparison: run the master Excel workbook against the sample and export key result sheets to CSV (or to a standard output format).
3. Run the migrated LibreOffice workbook with the same dataset and export the same sheets.
4. Automate comparison with a simple diff tool or script (Python pandas compare, CSV diff). Highlight numeric tolerance differences.
5. Functional tests: manually execute macros or key workflows and record pass/fail.
6. Performance checks: large workbooks and many formulas can be slower in Calc; test on target hardware.
7. User acceptance: get the template owners and 2–3 end-users to verify results and workflow comfort.

Fallback options if things break

• Dual-format approach: maintain an .xlsx master in Excel for macro-heavy processes and provide .ods or simplified templates for routine use.
• Hosted Excel: keep a small number of Excel licences (or use Excel Online) on a shared desktop or virtual machine for legacy tasks.
• Rebuild as server process: move Power Query/ETL to a server-side script (Python/R/SQL) and output .ods/.xlsx for users.
• Template marketplace services: buy migration-friendly templates or contract a conversion bundle from a specialist that guarantees compatibility and provides a support SLA.

Checklist: go/no-go for each template

Use this quick checklist during the pilot for every template:

• Inventory entry created and owner identified
• Impact score documented (1–5)
• Does the workbook contain macros? (Yes/No)
• Are Power Query/Query tables used? (Yes/No)
• Are modern Excel-only functions used? (e.g., LET, LAMBDA, XLOOKUP)
• Can the workbook be saved as .ods without critical loss? (Yes/No)
• Do all critical outputs match within tolerance after conversion? (Pass/Fail)
• User acceptance test passed? (Pass/Fail)
• Rollback plan documented and tested? (Yes/No)

Licensing, templates marketplace and customisation services

Moving to LibreOffice reduces licence fees, but migration has costs: staff time, developer hours and possible third-party services. Consider buying a migration bundle from a templates marketplace that includes:

• Pre-converted templates for UK SMEs (VAT, payroll summaries, monthly P&L, cashflow forecasts) in both .xlsx and .ods formats.
• Customisation services to fit UK accounting rules and Making Tax Digital (MTD) flows.
• Macro conversion support and testing SLA.
• Clear template licensing: permit internal use, modification and redistribution rules so you stay GDPR-compliant and auditable.

What to ask a vendor

• Do you provide both .xlsx and .ods versions?
• Is macro code audited and converted with explanation of changes?
• Do you include a test harness and sample data for UAT?
• Are updates and support included for a subscription or one-off fee?

Cost-saving reality check

Switching to LibreOffice can save licence costs immediately, but total cost of ownership depends on migration effort. Typical cost drivers:

• Volume and complexity of templates
• Number of macros to convert
• Training time for staff (LibreOffice UI differs from Excel)
• Ongoing support and maintenance

Many UK SMEs find a hybrid approach delivers the best ROI: keep a small number of Excel licences for specialised tasks and switch the majority of users to LibreOffice. This reduces subscription cost while limiting conversion effort.

2026 trends to leverage

• On-premise LLMs and private AI: since late 2025, some SMEs prefer running local AI tools for data processing; LibreOffice workflows can integrate with local Python scripts and local LLMs for document automation without moving data to the cloud.
• Standardised template bundles: marketplaces now offer certified templates for UK tax and reporting — choose bundles that include both formats and a migration guarantee.
• Automation via Python: Python scripting for LibreOffice (UNO) matured in 2024–25; consider rewriting complex Excel macros as Python scripts for better long-term maintainability.

Real-world case study (anonymised)

A UK consultancy with 35 staff replaced 80% of its desktops with LibreOffice in early 2025. They catalogued 120 templates, prioritised 15 for the pilot and converted 9 without macros. Three macro-heavy templates were kept on a single Excel VM and automated via scheduled tasks. They saved annual licence spend and invested in a migration bundle that provided .ods/.xlsx dual templates plus conversion support — net positive in month 7 after project start.

Actionable migration plan (timeline)

1. Week 0–2: Inventory and scoring.
2. Week 3–6: Pilot conversion of top 10 templates and build test harness.
3. Week 7–10: Convert medium complexity templates and train users.
4. Week 11–16: Deploy broadly, keep Excel VM for exceptions, and begin decommissioning Excel licences where possible.

Final checklist before you flip the switch

• All critical templates pass the Golden-run comparison
• Macro-heavy tasks have a documented fallback (Excel VM, server scripts)
• Users trained on key differences and support contact provided
• Licensing and template ownership documented
• Maintenance plan in place for future changes

Key takeaways

• Audit first. You can’t migrate what you haven’t catalogued.
• Test thoroughly. Use sample data, automated comparisons and UAT.
• Expect to rewrite macros. Simple macros often import; complex ones usually need a rewrite or a kept-Excel fallback.
• Adopt a hybrid approach. It often offers the best balance between cost savings and operational continuity.
• Buy migration-ready bundles if you lack in-house skills. Vendors that supply .ods/.xlsx pairs, testing and customisation will accelerate delivery.

Want help migrating templates — or want a ready-made bundle?

We build and convert UK-focused templates (VAT, cashflow, management accounts), provide macro conversion services and offer migration bundles with a guaranteed test suite. If you want a quick compatibility audit or a pilot conversion of up to 10 templates, contact our team for a fixed-price pack — we’ll return a compatibility report, converted files and a rollout plan.

Ready to start? Get a migration audit or browse our marketplace for dual-format bundles and conversion services tailored to UK SMEs.

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