Tax return software for a practice has to file every return the firm prepares: individual returns with all their supplementary pages, partnership and trust returns, Company Tax Returns with iXBRL accounts and computations, and now Making Tax Digital for Income Tax quarterly updates and year end returns. HMRC publishes lists of software that has passed its testing, but it does not endorse any product and inclusion is not a judgement on quality, so the firm still has to check coverage, workflow and security itself.
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Which returns does the software have to cover?
Start with a count of the returns the firm files each year by type, because HMRC’s own services no longer cover all of them:
- Individual returns (SA100). HMRC’s Self Assessment for Agents online service can send the SA100 and most supplementary pages. Agents must register for that service whether they file through HMRC’s online services or commercial software.
- Partnership returns (SA800) and trust and estate returns (SA900). HMRC’s guidance for agents says commercial software allows the SA800 and SA900 to be filed, and HMRC’s page on the SA900 says that to send it online you will need to buy software for trust and estate returns.
- Company Tax Returns (CT600). HMRC’s free File your accounts and Company Tax Return service closed on 31 March 2026. From 1 April 2026 companies should use commercial software, and a paper return is only possible with a reasonable excuse or when filing in Welsh.
- MTD for Income Tax. Clients brought into MTD must send quarterly updates and their tax return through compatible software.
Our page on filing a CT600 without HMRC’s free service covers the company side for clients who used to file themselves.
What does it mean when HMRC lists a product?
HMRC publishes a list of Self Assessment commercial software suppliers. It says these suppliers can submit one or more elements of the tax return and supplementary pages, that HMRC will accept valid returns for the products listed, and that HMRC cannot recommend or endorse one product over another. For each supplier the list shows whether the product is for agents, individuals or both, and for each return type which schedules are supported and whether attachments and amendments are supported. Some suppliers support all schedules; others list specific forms only.
The Corporation Tax list works the same way. Suppliers have given evidence that they can produce one or more elements of a Company Tax Return, and the list shows whether each can produce and submit the CT600, submit iXBRL documents, and is suitable for self filers. HMRC states that it does not carry out any security testing of these products and encourages users to ask suppliers about security. HMRC’s XBRL guide adds that inclusion in its list does not imply any judgement on the general quality of the software; it simply indicates that the software meets certain basic criteria, including producing technically valid iXBRL output.
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What should be checked for Self Assessment work?
Use the HMRC list to confirm the basics, then test the product against the firm’s real client mix:
- Schedules. Check every supplementary page the firm uses. The list shows, for example, products covering SA100 with SA101 to SA109 and partnership products covering SA800 with SA801 to SA804.
- Attachments and amendments. Some clients need computations or explanations attached, and amended returns must go through the same software.
- Prepopulation. HMRC says some commercial software can get details from HMRC to help an agent complete a client’s return; check with the supplier whether the product includes it.
- Partnership flow through. Partnership profit shares should carry into each partner’s individual return without rekeying.
- Trust returns. If the firm has even a few trust clients, the product must handle the SA900 and its supplementary pages.
Build in a client approval step before submission. Our page on client approval before filing covers what evidence to keep.
What does Company Tax Return software need to do?
A Company Tax Return is more than the CT600. HMRC’s guidance on the closure of its free service says to make sure the chosen software can file the CT600, the Corporation Tax computation and the company accounts. HMRC’s guidance on accepted taxonomies says all Company Tax Returns for accounting periods ended after 31 March 2010 must be submitted using iXBRL for accounts and computations, and that the accounts and computations must be fully tagged.
The XBRL guide names the taxonomies used: the FRC accounts taxonomy for accounts under IFRS, FRS 101, FRS 102, FRS 102 Section 1A and FRS 105; the Corporation Tax computational taxonomy for the computation; and the Detailed Profit and Loss taxonomy for any detailed profit and loss statement submitted. HMRC’s taxonomy page lists which version may be used for which accounting periods, so the software must keep up with new versions.
HMRC’s supplier list separates three ways of producing iXBRL: integrated software applications, managed tagging services, and conversion software. A firm that prepares accounts in its own accounts production package and computations in its tax package needs the two to produce a single valid submission. Our page on iXBRL tagging for company tax returns explains what has to be tagged, and our companion page on choosing accounts production software covers the accounts side.
How does MTD for Income Tax change the choice?
From 6 April 2026, sole traders and landlords with qualifying income over £50,000 for 2024 to 2025 should be using MTD for Income Tax, with the threshold falling to £30,000 from April 2027 and £20,000 from April 2028. HMRC’s guidance says compatible software must create, store and correct digital records, send quarterly updates and submit the tax return. For 2026 to 2027 that return must be submitted through compatible software by 31 January 2028.
A firm can use more than one product, for example the client’s bookkeeping software for quarterly updates and the firm’s tax software for the year end return, but HMRC says only one product can be used for each separate submission and the products must work together. Agents work through an agent services account, which is different from the HMRC online services for agents account, and a client can have one main agent and any number of supporting agents. Check that the tax package supports the role the firm will take for each client. Our page on main and supporting agents under MTD explains the split.
How should a practice compare packages?
| Question | Why it is asked |
|---|---|
| Does it file every return type the firm prepares, including SA800, SA900 and CT600 with iXBRL? | Gaps force a second product and duplicate data entry. |
| Does it handle MTD quarterly updates and the year end return, or connect to software that does? | Clients are joining MTD in stages from 2026 to 2028. |
| Does it integrate with the firm’s accounts production and practice management software? | Rekeying figures between systems is where errors start. |
| How are amendments, attachments and rejected submissions handled? | These take time out of season. |
| What security and access controls does the supplier provide? | HMRC does not security test listed products. |
| How is it priced: per user, per client, per return or by module? | Module pricing can change the total cost for a small number of trust or partnership returns. |
Illustration only. A firm files 500 individual returns, 30 partnership returns, 12 trust returns and 120 Company Tax Returns a year. Its shortlisted product covers SA100 and CT600 well but lists no SA900 support. The firm either adds a second product for 12 trust returns, with separate training and logins, or picks a suite that covers all four, and compares the total annual cost of each route.
What mistakes do practices make?
- Choosing on individual returns alone and finding out in January that trust or partnership returns are not covered.
- Treating an HMRC listing as a quality or security endorsement.
- Not testing iXBRL output from the accounts and tax packages together before the first live CT600.
- Ignoring which taxonomy versions the software supports for the periods being filed.
- Planning MTD around the tax package without checking how it connects to clients’ bookkeeping software.
Solar Protect runs fee protection schemes for accountancy and bookkeeping practices. See how our accountant schemes work or read fee protection schemes for accountants.
Related Accountapedia entries
- Choosing practice management software
- Choosing software for MTD for Income Tax
- Choosing payroll software for a payroll bureau
- Choosing accounts production software
- Xero, QuickBooks or Sage for your clients
Sources
- GOV.UK: Self assessment for agents online service
- GOV.UK: Self assessment trust and estate tax return sa900
- GOV.UK: Closure of the service to file your company accounts and tax return
- GOV.UK: Self assessment online commercial software suppliers
- GOV.UK: Self assessment commercial software suppliers
- GOV.UK: Corporation tax commercial software suppliers
- GOV.UK: Xbrl guide for uk businesses
- GOV.UK: Taxonomies accepted by hmrc
- GOV.UK: Find out if and when you need to use making tax digital for income tax
- GOV.UK: Choose the right software for making tax digital for income tax
Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.