Switching Accounting Software? A Practical Migration Checklist for Accounting Firms

Map Your Existing Accounting Environment Before Any Data Moves

Before any migration begins, your firm must establish full visibility of the current accounting environment. Most migration failures begin with incomplete system mapping and undocumented dependencies.

Document Your Current Setup

Your team must build a complete inventory of how the current system operates in practice, not just how it was originally configured.

• List every integration, add-on, and third-party data source connected to your accounting platform, including payroll, expense tools, and bank feeds.
• Record which clients have portal access and identify how each client submits data into the system.
• Confirm HMRC ASA authorisation status separately for MTD VAT and MTD ITSA obligations across all client files.

Assign Ownership Before Anything Moves

Without defined ownership, migration timelines drift, and accountability becomes unclear during go-live pressure.

• Appoint one migration lead with authority to approve the final go-live date without secondary approval delays
• Assign each client file to a specific staff member to ensure continuity of knowledge during data transfer
• Fix the go-live date around a quarter-end or year-end and document it internally so no informal early switch occurs

Checklist for Successful Accounting Software Migration

Firms that skip pre-import audit steps typically spend the first reporting cycle correcting avoidable discrepancies rather than producing accurate management accounts.

Audit and Clean Your Data Before You Import It

This stage determines whether your new system starts clean or inherits legacy issues that are harder to trace after migration.

• Run a full trial balance in the existing system and export it as the official pre-migration baseline.
• Clear all unreconciled bank items, suspense entries, and duplicate transactions before any export takes place
• Remove or archive inactive clients and dormant ledgers that do not require migration.
• Separate historical data into two categories: data that must migrate and data that remains in a read-only archive.

Remap Your Chart of Accounts Before You Import

Your chart of accounts is the structural backbone of financial reporting. If it is misaligned, every downstream report becomes unreliable.

• Map every nominal code from the old system to its equivalent in the new platform before any data import begins.
• Validate VAT treatment codes, including standard rate, zero rate, exempt, and out of scope, to ensure consistent tax reporting logic.
• Check that the expense categories align with the required fields used in MTD ITSA reporting.
• Require formal sign-off from the migration lead before initiating any data transfer.

This step directly determines whether your VAT returns and MTD submissions remain accurate after migration.

Test Workflows in a Controlled Environment Before Go-Live

Testing ensures your firm can complete real accounting tasks in the new system before exposing client data. A migration is not validated by login access. It is validated by workflow performance.

• Import a test client and complete a full accounting cycle, including bank reconciliation and journal postings.
• Test the bank feed accuracy and confirm that the transaction categorisation logic is functioning correctly.
• Run document capture and invoice processing workflows to ensure operational continuity.
• Simulate an MTD submission cycle to verify HMRC data transmission is active.
• Complete the HMRC ASA re-authorisation in the new system and confirm the activation status.

If ASA reauthorisation is not verified, your firm is not MTD-ready, even if everything else appears functional.

Train Your Team First, Then Phase the Client Portal

Internal readiness must always precede client exposure. Without this sequencing, the support load increases sharply after go-live.

• Train all internal staff on navigation, posting workflows, and reporting functions before enabling any external access
• Allow a structured adjustment period of two to four weeks before activating client portal functionality
• Prepare a concise client communication explaining what is changing, what they must do, and when they must act
• Delay activation of document upload and client access until staff can resolve queries without escalation

The most common failure point is premature client onboarding before internal confidence is established. Firms that phase rollout reduce reporting errors and client confusion significantly.