Moving a whole client book to new software sounds terrifying. It doesn't have to be. The trick is to move in small waves and to standardise everything before the first client switches.

Where do most migrations go wrong?

They try to move everyone in one weekend. A firm decides on a new system on Monday, promises the partners it'll be live by month-end, and spends the next four weeks firefighting broken VAT returns.

Treat it as a project, not a switch. Pick a start date that isn't near a filing deadline, give yourself a clear run, and accept that the first few clients will teach you what your process should be.

How should you sequence the move?

In waves. Group your clients by complexity and move the simplest first:

  • Wave 1 — five to ten clean limited companies with no payroll and simple VAT. These prove your process.
  • Wave 2 — the bulk of your book, once your templates and checklists are settled.
  • Wave 3 — the complex ones: multiple VAT schemes, CIS, messy histories.

Keep the previous software in read-only access until you've reconciled opening balances in the new one. That single habit removes most of the fear.

What do your clients actually need from you?

Far less than you think — but they need it clearly. One short email per client, sent before you touch anything, covering three things: what's changing, the date it happens, and the one action they need to take (usually "approve the connection" or "nothing at all").

Silence is what worries clients, not change. A two-line "you're moving to a faster system next Tuesday, we've handled everything" email prevents a dozen phone calls.

Where automation earns its keep

The repetitive parts — pulling bank feeds, mapping the chart of accounts, sending the client notice — are exactly the parts worth automating once and reusing for every wave. That's the difference between a migration that costs you a month and one that runs in the background while you keep serving clients.

If you'd like to see how AccountsBridge handles client migration end to end, book a 15-minute demo and we'll walk you through a real move.