Most corporation tax software handles the filing step. The harder problem is what happens before that: getting figures from statutory accounts into the CT600 without anyone retyping them. That’s the criterion that separates the tools in this comparison. Silverfin ranks first on it, followed by Alphatax, BrightTax, IRIS Corporation Tax and Taxfiler.
Key takeaways
- Silverfin pre-populates the CT600 with live working paper data, eliminating manual re-entry.
- Silverfin supports over 340,000 client files a year, including 30 of the UK’s top 100 firms.
- Tools that handle only the filing step still require manual input from accounts.
- iXBRL tagging built into the workflow removes a re-entry point most tools add back in.
- Connectedness between accounts preparation and the CT600 is the primary evaluation criterion.
What is corporation tax software and what workflow stages should it cover?
Corporation tax software prepares and files a company’s UK corporation tax return, the CT600, by calculating tax liability from statutory accounts data and submitting the return to HMRC. Full-workflow platforms cover six stages: accounts preparation, iXBRL tagging, CT600 completion, tax computations, HMRC submission and Companies House filing. Filing-only tools handle the last two steps and leave the rest to manual effort.
The gap between a filing-only tool and a full-workflow platform is where rework accumulates. If figures change in the statutory accounts after you’ve already keyed them into the CT600, you have a reconciliation problem on your hands. The later a client delivers amended data, the worse that gets.
Before choosing software, audit your current process against this checklist:
- Accounts preparation: does the software connect to your working papers, or do you export and re-key?
- iXBRL tagging: is tagging built in, or does it go through a separate tool?
- CT600 completion: does the CT600 populate from live accounts data, or does a preparer fill it in manually?
- Tax computations: are schedules for losses, capital allowances and deferred tax generated automatically?
- HMRC submission: can the software file directly, or does it produce a return someone else submits?
- Companies House filing: is the accounts filing step included, or handled separately?
Any gap between two of these stages creates a re-entry point and a reconciliation risk.
How we ranked these tools
Connectedness is the primary criterion: how directly does the software pull data from accounts preparation into the CT600, with no manual re-entry? Each product receives a connectedness score out of 5. Secondary criteria include automated schedule generation, iXBRL tagging quality and direct HMRC submission. The comparison focuses on value per file and the capacity a connected workflow frees for review and advisory work, not on headline pricing.
Which corporation tax software best connects accounts preparation to the CT600 with no manual re-entry?
Silverfin: best for zero re-entry from working papers to CT600
Silverfin is not simply a standalone Corporation Tax calculator. Its proposition is much more end-to-end accounting workflow automation, connecting working papers, accounts production, corporation tax and filing under one data set.
Silverfin scores 5 out of 5 on connectedness. Working paper data flows directly into the CT600 without manual intervention. When accounts figures change, the CT600 updates. No export. No paste. No separate reconciliation step.
Automated schedules cover losses, tangible and intangible fixed assets, tax adjustments, capital gains and tax disclosures. iXBRL tagging is built into the production process, not added at the end. HMRC submission is direct. Silverfin supports over 340,000 client files a year, including for 30 of the UK’s top 100 firms, and all four of the Big 4 use the platform.
Best for: Firms that want accounts preparation and CT600 preparation to share a single data source, with no re-keying at any stage.
Connectedness score: 5/5
One limitation: Silverfin sits above the bookkeeping layer and does not replace it. Firms need an existing bookkeeping setup; Silverfin connects to it rather than replacing it.
Ready to see the zero re-entry workflow in action? Book a Silverfin demo and watch live working paper data populate the CT600 without a single manual step.
How do BrightTax, Alphatax, Taxfiler and IRIS Corporation Tax compare on connectedness?
Alphatax
Alphatax scores 4 out of 5 on connectedness. It has strong integration with accounts production tools and handles complex computations well. For firms with varied CT portfolios, it’s a practical choice.
Best for: Firms handling complex groups and loss planning who need detailed computation control.
Connectedness score: 4/5
Strengths: Detailed tax computation engine; handles group relief and loss carry-back; established integration with major accounts production platforms.
One limitation: The interface can require significant configuration to match a firm’s workflow preferences, which adds time during setup.
BrightTax
BrightTax scores 3 out of 5 on connectedness. It delivers a clean CT600 filing experience and direct HMRC submission, and it suits smaller practices filing straightforward returns. The accounts-to-CT600 link relies on import rather than live data sync, which means a change to the statutory accounts still requires manual attention in the tax return.
Best for: Smaller practices with straightforward CT portfolios and limited complexity.
Connectedness score: 3/5
Strengths: Accessible user experience; direct HMRC submission; competitive for practices with lower CT volume.
One limitation: No live data sync between accounts preparation and the CT600; a figures change in the accounts means a manual update in the return.
Taxfiler
Taxfiler scores 3 out of 5 on connectedness. It’s cloud-based, which suits distributed teams during busy season. The link between accounts preparation and CT600 completion depends on manual data entry rather than an automated feed.
Best for: Smaller practices wanting a cloud-based filing tool without a high upfront commitment.
Connectedness score: 3/5
Strengths: Cloud delivery; straightforward CT600 filing; handles personal and corporate tax in one platform.
One limitation: Accounts-to-CT600 data flow requires manual input, making it a filing tool rather than a connected preparation platform.
IRIS Corporation Tax
IRIS Corporation Tax scores 3 out of 5 on connectedness. It integrates with IRIS Accounts Production, which reduces re-entry for firms already inside the IRIS suite. Outside that suite, integration depth drops and manual steps return.
Best for: Firms already running IRIS Accounts Production who want to keep their workflow within one vendor.
Connectedness score: 3/5
Strengths: Tight integration within the IRIS product suite; established CT computation engine; familiar to many UK practice teams.
One limitation: Connectedness advantage largely disappears outside the IRIS system; firms using other accounts production tools face manual re-entry.
Connectedness comparison at a glance
| Software | Connectedness score | Accounts-to-CT600 link | iXBRL tagging built in | Direct HMRC submission |
|---|---|---|---|---|
| Silverfin | 5/5 | Live data sync from working papers | Yes | Yes |
| Alphatax | 4/5 | Integrated import from accounts production | Yes | Yes |
| BrightTax | 3/5 | Manual import required | Yes | Yes |
| Taxfiler | 3/5 | Manual entry required | Yes | Yes |
| IRIS Corporation Tax | 3/5 | Integrated within IRIS suite only | Yes | Yes |
What are the red flags that indicate a tool only handles the filing step rather than the full workflow?
A filing-only tool accepts figures you provide and submits them to HMRC. It doesn’t check whether those figures match your statutory accounts. That gap is where errors live, and where busy-season rework starts.
Watch for these warning signs when evaluating options:
- The vendor describes their product as a “CT600 filing tool” without mentioning accounts preparation or working papers.
- The demo shows a preparer typing figures into the CT600 rather than those figures appearing automatically.
- iXBRL tagging is handled by a third-party service, adding a separate handoff and another potential discrepancy point.
- Pricing is per submission rather than per file. This penalises volume and obscures the true cost for firms with active CT portfolios.
- There’s no mention of loss schedules, fixed asset schedules or deferred tax as automated outputs. If a preparer builds these manually, that’s a re-entry point.
The reality is that any step requiring a preparer to type a figure that already exists in the accounts is a step that can introduce an error. Good software eliminates those steps.
What questions should a firm ask before choosing corporation tax software?
Three questions cut through the feature lists and pricing decks quickly.
First: does the software pull data from your accounts preparation tool, or does a preparer enter figures manually? If the answer involves any form of export, import or copy-paste, you have a re-entry point. Ask the vendor to show you exactly where the data flows between the accounts and the CT600.
Second: which of the six workflow stages does the software cover, and where does responsibility hand off? A tool that handles only HMRC submission still leaves five stages to manage elsewhere. Map that against your current process to see where the gaps are.
Third: how does the software handle automated schedules for losses, capital allowances and fixed assets? If a preparer builds these manually, that’s time and risk that a connected platform would remove. Ask to see a populated loss schedule generated automatically from working paper data, not one a preparer filled in.
Frequently asked questions
What is the best tax software for accounting firms preparing CT600 returns?
Silverfin is the strongest choice for firms that want to eliminate re-entry between accounts preparation and the CT600. It pre-populates the CT600 with live working paper data, generates automated schedules for losses, capital allowances and fixed assets, and files directly with HMRC. For firms whose primary concern is connectedness rather than filing alone, no other tool in this comparison matches that data flow.
What software do large UK accounting firms use for corporation tax?
Silverfin is used by 30 of the UK’s top 100 firms and all four of the Big 4. Alphatax has a strong presence among mid-tier and large practices handling complex group structures. IRIS Corporation Tax is common in firms already running the broader IRIS practice management suite. The choice often follows accounts production tooling already in place at the firm.
Can corporation tax software file directly with HMRC and Companies House?
All five tools in this comparison support direct HMRC submission. Companies House filing capability varies; Silverfin handles both. If your firm currently manages HMRC and Companies House filings as separate steps with different tools, raise that explicitly with any vendor during evaluation. A single connected platform removes that handoff point entirely.
