Why practices are reviewing desktop CT software

Corporation Tax work has become more workflow-heavy. The return package includes the CT600, computations, accounts, any supplementary pages, attachments, validation, client approval, submission evidence, amendments, and payment follow-up. A desktop install can still file returns, but many practices now want a cleaner team workflow.

The cost is not only the annual licence. Every desktop update can mean waiting for an IT person, checking local installs, dealing with staff machines, and losing billable time while the tax team waits for the software to be ready again.

The HMRC and Companies House joint filing service closure also changed client expectations. Directors who previously self-filed may now ask practices for help, and practices need a repeatable way to absorb those returns without adding fragile local installs or manual checklists.

Migration is not only data export

The mistake is treating migration as "get the old files out and import them somewhere else." For CT600 work, the useful migration unit is the client workflow: source data, prior-year return, computation assumptions, supplementary-page history, approvals, submission evidence, and payment follow-up.

Before switching systems, identify what must survive the move:

client company details, UTRs, accounting periods, and filing deadlines;
prior-year CT600 and computation outputs;
iXBRL accounts and computations, or the source files used to create them;
loss schedules, capital allowance pools, group relief history, and director loan balances;
supplementary-page triggers and prior review decisions;
client approval records and HMRC submission or rejection evidence;
payment references, repayment claims, and unresolved follow-up tasks.

Build a CT600 migration checklist

A good migration checklist lets a practice move clients in batches rather than pausing the whole tax department. Start with current and next-deadline clients, then backfill lower-risk history as needed.

List all Corporation Tax clients, filing deadlines, and responsible team members.
Flag clients with specialist work: CT600A, CT600C, CT600L, CT600N, CT600P, losses, or repayment claims.
Export the last filed return, computation, accounts, and HMRC response evidence where available.
Capture standing schedules such as losses, capital allowances, group claims, and loans.
Decide which clients need full historical import and which only need opening balances and current-year workflow.
Run a pilot on a small client set before moving deadline-critical work.
Document how preparer, reviewer, partner, and client approval steps work in the new system.

Desktop workflow pain points to remove

Migration should make the work easier to control, not merely replace one interface with another. Look for points where desktop workflows have been hiding operational risk.

Local file dependency: returns trapped on one machine or one user's profile.
Update support costs: each tax-year update can create an IT call-out, staff downtime, and uncertainty over which machines are running the current version.
Weak review trail: final CT600 output saved, but no clear evidence of who reviewed which assumptions.
Seat friction: preparers, managers, and partners avoiding the software because licences are scarce.
Attachment drift: accounts or computations updated after the CT600 was prepared, without a fresh approval pack.
Manual client approval: email chains that do not clearly connect the approved pack to the filed return.
Post-filing gaps: HMRC response, payment reference, repayment claim, or rejection handling saved outside the tax workflow.

What to test before switching

Practices should test the returns that create real friction, not only a clean sample company. Include an owner-managed company with a director loan, a loss case, an amended return, and at least one supplementary-page case.

Can the team prepare a CT600 from the client's actual records?
Can reviewers see the computation and source assumptions without opening local files?
Are iXBRL accounts and computations attached to the exact approved version?
Does the system support the supplementary pages the practice actually files?
Can a client approval pack be retained with the final submission evidence?
Can rejected returns and amendments be handled without losing the original trail?

How to time a migration around renewals

Many practices renew tax software annually. The best migration window is usually before renewal pressure turns into a rushed decision. Map the desktop licence renewal date against the Corporation Tax deadline calendar, then choose a pilot period with enough real returns but no cluster of deadline-critical cases.

Include update support in the renewal calculation. If every release needs an outside IT person or internal admin time, the real cost of the desktop system is higher than the licence line alone. If the renewal date is close, avoid trying to move every historical return immediately. Move the current-year workflow and the data needed to file safely, then preserve exports from the old system for reference.

How Robocount supports practice migration

Robocount is browser-based Corporation Tax software for CT600 preparation, review, and filing workflows. It is designed for practices that want the return package, approval trail, supplementary pages, and Government Gateway submission evidence in one modern workflow.

No desktop install for preparers, reviewers, and partners.
Browser-based updates without practice-by-practice IT call-outs.
Structured CT600 workflow for practices and company directors.
Supported supplementary-page guides and review areas connected to the main return.
API and MCP-native surface for firms building automated intake or AI-assisted review.
Clearer path from preparation to approval to filing evidence.

FAQ

Should a practice migrate all historical Corporation Tax data?

Not always. Keep the old records accessible, but prioritise the current-year workflow, standing schedules, prior-year comparatives, unresolved claims, and evidence needed for safe filing.

What is the biggest migration risk?

Losing context. A CT600 output is not enough if the practice also needs loss schedules, capital allowance pools, director loan history, group relief evidence, client approval, and HMRC response records.

Can browser-based CT600 software work for teams?

Yes, if the workflow supports preparation, review, approval, filing status, and evidence retention. The point is to reduce dependency on local installs and isolated files.

When should migration happen?

Ideally before annual renewal pressure and away from the heaviest deadline cluster. Pilot with real client cases, then migrate in batches.

Useful official references

This guide is general product and workflow information for accountancy practices, not tax advice.

Migrating CT600 work from desktop Corporation Tax software.