IRIS, TaxCalc, and Digita (CCH) are the three main software suites used by UK accounting practices for tax compliance, accounts production, and practice management. They are not equivalent products aimed at the same buyer. The differences in cost, integration quality, and usability are significant enough that choosing the wrong one for your firm's size and workflow is a mistake that takes years to undo.
None of the three publishers lists full pricing on their websites for practice-level suites. The figures below come from AccountingWEB practitioner discussions and are indicative rather than guaranteed quotes.
IRIS is consistently reported as £5,000 or more per year for a small-to-medium practice with standard modules. Practitioners note that costs increase at renewal and that adding modules is expensive. The product is modular — personal tax, company tax, accounts production, practice management, and payroll are separate purchases that integrate together.
Digita is typically reported at around £3,000 per year, though this varies significantly by module selection and firm size. Like IRIS, modules are sold separately and integrate via a shared client database.
TaxCalc publishes entry-level pricing from £52 including VAT, and its practice suite is generally quoted in the £1,000–£2,000 range for small-to-medium practices. The Practice Manager module is included free as standard rather than sold separately. TaxCalc offers a 14-day free trial of the full suite.
All three products handle personal tax returns (SA100 and supplementary pages), company tax returns (CT600), and partnership returns (SA800). The compliance coverage is broadly equivalent for standard cases. The differences appear at the edges: complex mixed-income cases, trust returns, non-domicile situations, and handling of the new MTD ITSA quarterly submissions.
IRIS is reported to have a 98% HMRC acceptance rate for submissions and handles the full range of tax return types including trusts and estates. Its automation for standard cases is strong — bulk letter generation (engagement letters, cover letters, SA302 summaries) works from a single client record update.
TaxCalc uses a SimpleStep interview format that guides preparers through returns section by section. Practitioners who have switched from IRIS to TaxCalc consistently describe it as "much quicker" for standard SA100 and CT600 cases. The SimpleStep approach reduces errors on less-experienced staff handling routine returns.
Digita's personal tax module is well-regarded for complex personal tax cases once users are familiar with it. The criticism is that sole trader cases require manual add-back entries that other products handle automatically, and the module does not integrate cleanly with the accounts production module — data must be manually imported rather than flowing automatically.
This is where the products diverge most sharply in practitioner feedback.
IRIS Accounts Production generates statutory accounts automatically from trial balance input. iXBRL tagging for Companies House filing is handled automatically. The product handles UK GAAP, micro-entity accounts, and charity accounts under SORP. Accounts generate quickly and the data flows directly into the CT600 module without re-entry. The complaint is that it requires careful setup and the interface is not particularly modern.
TaxCalc Accounts Production won the AccountingWEB award for Best Accounts Production software in both 2020 and 2021. Practitioners describe it as significantly faster than IRIS for standard limited company and LLP accounts. iXBRL tagging is automatic, Companies House filing is built in, and the product handles groups, charities, and LLPs. The data flows from accounts production into the tax module without manual transfer.
Digita Accounts Production has usability problems that practitioners mention consistently. It is described as "extremely slow, crashes frequently, overly complicated" in AccountingWEB discussions. Manual mapping of accounts formats and notes is required rather than automatic generation. The accounts-to-tax data flow requires a manual import step. Practitioners who use it tend to describe getting value from it only after a significant learning curve.
Practice management — client database, deadline tracking, task assignment, time recording, billing — is where the cost and integration differences matter most in day-to-day operation.
IRIS Practice Management sits at the centre of the IRIS ecosystem. Updating a client record in one module propagates across all others. Automated letter generation pulls client data without manual re-entry. For firms that are fully inside the IRIS ecosystem, this integration is genuinely valuable. The problem is that firms often use cloud accounting software (Xero, QuickBooks) for their clients' bookkeeping, and IRIS Practice Management does not integrate with those as smoothly as with its own modules.
TaxCalc Practice Manager is included free with the suite (rather than sold as a separate module). It includes deadline management, a SimpleStep checklist system, and a Communications Centre for tracking chargeable activity and client profitability. The integration between Practice Manager and the tax/accounts modules is clean — filing deadlines populate automatically from return creation.
Digita has the weakest practice management integration of the three. Modules work relatively independently, with data flowing between them only through manual export and import steps. Firms that choose Digita often run a separate practice management tool alongside it.
| Feature | IRIS | TaxCalc | Digita |
|---|---|---|---|
| Annual cost (approx.) | £5,000+ | £1,000–£2,000 | ~£3,000 |
| Accounts production | Strong — fast for high volume | Strongest — award-winning, fast | Weak — slow, manual steps |
| Tax compliance | Comprehensive, 98% HMRC acceptance | Comprehensive, SimpleStep interface | Good for complex personal tax |
| Practice management | Best-in-class integration (within IRIS) | Good — included free, clean deadlines | Poor — largely manual between modules |
| MTD ITSA ready | Yes | Yes | Yes (CCH iFirm for cloud clients) |
| Best suited to | Mid-large practices (20+ staff) | Small-medium practices (1–15 staff) | Medium practices with complex personal tax |
The AccountingWEB community, which is the most active public forum for UK accountants, shows a clear pattern in switch discussions. Practices that leave IRIS for TaxCalc are, in the vast majority of cases, satisfied with the switch. The primary drivers are cost and speed, not a loss of functionality. The most common comment is that TaxCalc handles standard accounts and tax work faster than IRIS at a fraction of the price.
Digita has fewer enthusiastic advocates in public forums. It persists largely because of familiarity — practices that have used it for years and built workflows around it are reluctant to switch rather than actively recommending it to others.
IRIS retains its position in larger practices because its integration advantage is real at scale. A firm with 30 staff handling thousands of client returns benefits from automated letter generation, bulk deadline management, and the shared client record in ways that a 5-person practice does not.
None of the three products integrates cleanly with every combination of tools a modern practice uses. Firms running Xero or QuickBooks for client bookkeeping, combined with a practice management tool, combined with a separate document management system, combined with a billing platform, end up with multiple systems that do not share data automatically. Custom integration work — connecting the client record in TaxCalc or IRIS to the firm's CRM, or building a client portal that surfaces deadline status from the practice management tool — is the most common bespoke requirement for accounting practices rather than replacing the compliance software itself.