Personal tax software for Self Assessment covers a wide range of tools, from simple apps designed for individuals filing a single return, to professional compliance platforms used by accountants managing hundreds of clients. The right choice depends entirely on who is filing and how complex the tax position is.

This guide reviews the leading options in 2026 and explains what to look for whether you are filing your own return or acting as an agent for clients.

Who needs to file a Self Assessment return?

HMRC requires a Self Assessment return from anyone whose tax affairs fall outside the PAYE system or who has income above certain thresholds. Common reasons include:

  • Self-employment income above £1,000
  • Property rental income
  • Income from savings, investments, or dividends above the relevant allowances
  • Capital gains above the annual exempt amount
  • Income above £100,000 (which reduces the personal allowance)
  • Child Benefit receipt where household income exceeds £60,000
  • Foreign income
  • Directors of limited companies

If HMRC has issued a notice to file, you are legally required to submit a return by the deadline: 31 October for paper returns, 31 January for online returns. A late filing penalty of £100 applies immediately, with further charges accruing after three months.

Software for individuals filing their own return

If you are filing your own Self Assessment, HMRC's free online service at tax.service.gov.uk is available to all registered taxpayers. It covers the standard SA100 form and most supplementary pages. It is functional for straightforward cases but offers minimal guidance and no calculations until you have entered all data.

GoSimpleTax

GoSimpleTax is a popular option for individuals wanting a more guided experience than HMRC's own portal. It walks users through income and allowance fields with plain-English descriptions, calculates the tax due in real time, and files directly to HMRC. It supports most SA100 supplementary pages including rental income (SA105), employment (SA102), and self-employment (SA103).

Pricing is per return and relatively low, making it accessible for individuals. It is less suited to complex cases involving foreign income, trusts, or multiple sources.

TaxScouts

TaxScouts combines software with an accountant review service. Users enter their information and a qualified accountant checks the return before submission. This hybrid model suits people who want assurance without paying full accountancy fees. Pricing is fixed per return.

Untied

Untied is a mobile-first tax app targeted at freelancers, sole traders, and gig economy workers. It connects to bank accounts via Open Banking to import transactions, categorises income and expenses, and prepares the self-employment pages of the SA100. It is built with MTD for ITSA in mind and supports quarterly submission as the rules evolve.

Software for accountants managing client Self Assessment returns

For practices managing Self Assessment on behalf of clients, a professional compliance platform is essential. The individual-facing tools above are not designed for agent filing or multi-client management.

TaxCalc Personal Tax

TaxCalc's Personal Tax module is a full compliance tool for accounting practices. It supports the complete SA100 form set including all supplementary pages, files via the Government Gateway using agent credentials, and handles prior-year data and comparative returns. It integrates with TaxCalc's corporation tax and accounts production modules for firms handling both personal and company work.

IRIS Personal Tax

IRIS Personal Tax is the equivalent product in the IRIS ecosystem. It is well established in larger practices and integrates tightly with IRIS Practice Management and IRIS Payroll. The product covers all SA100 supplementary pages and supports MTD for ITSA. For firms already using IRIS for other functions, it offers a natural fit.

Digita Personal Tax (Thomson Reuters)

Digita is used in many of the larger UK accountancy firms. It offers deep functionality across the SA100 form set and integrates with Digita's accounts production and corporation tax products. It sits at the higher end of the pricing spectrum and is better suited to practices with significant volumes of complex personal tax work.

Xero Tax (personal tax module)

Xero Tax supports SA100 personal tax returns and can draw data directly from connected Xero client files. For practices with a predominantly Xero-based client base, this reduces manual data entry. The functionality is narrower than dedicated compliance platforms, but for straightforward employment and self-employment cases, it is a practical option.

MTD for ITSA and what it means for personal tax software

Making Tax Digital for Income Tax Self Assessment changes the filing model for sole traders and landlords from April 2026. Those with annual income above £50,000 must submit quarterly updates to HMRC, with a final declaration replacing the traditional SA100. The threshold drops to £30,000 from April 2027.

Software you choose now should be MTD for ITSA ready. This means it needs to support quarterly submission of income and expense totals, not just the year-end return. HMRC's recognised software list confirms which products have achieved this compatibility.

For a full comparison of your options, visit our tax software section.

What to look for when choosing personal tax software

  • HMRC recognition: The software must be on HMRC's list of recognised software for Self Assessment filing. Without this, electronic submission is not possible.
  • Supplementary page coverage: Confirm that the software supports all the pages relevant to your client mix. Foreign income, trusts, and partnership income require specific pages that not all tools include.
  • MTD for ITSA readiness: If you have clients who will be caught by MTD from April 2026, confirm the software supports quarterly updates.
  • Data import: The ability to import payroll data, bank feeds, and prior-year information saves significant time and reduces errors.
  • Filing deadline management: Practices benefit from tools that flag approaching deadlines and track submission status across the client base.

Key takeaways

  • Individuals can use HMRC's free online portal for straightforward returns; third-party tools like GoSimpleTax offer a more guided experience.
  • Accounting practices need professional compliance platforms such as TaxCalc or IRIS, which support agent filing and multi-client management.
  • MTD for ITSA requires software capable of quarterly submissions, not just year-end filing, from April 2026 for higher-income clients.
  • Always verify that your chosen software appears on HMRC's recognised software list before committing to it for client filings.
  • The Self Assessment filing deadline is 31 January for online returns; late filing penalties begin at £100 and increase over time.

Frequently asked questions

Can I file my Self Assessment return for free?

Yes. HMRC provides a free online Self Assessment filing service at tax.service.gov.uk. It covers the SA100 and most supplementary pages and is suitable for most straightforward cases. Third-party tools offer a more guided experience for a small fee, and some offer a free tier for simple returns.

What is the difference between personal tax software and practice compliance software?

Personal tax software aimed at individuals is designed for one-off or simple returns and does not support agent filing or managing multiple clients. Practice compliance software, used by accountants, allows filing on behalf of clients using HMRC agent credentials, handles multiple returns simultaneously, and typically covers the full range of SA supplementary pages and other return types such as CT600.

What happens if I miss the Self Assessment deadline?

A £100 late filing penalty applies immediately if a return is not submitted by 31 January. After three months, a further daily penalty of £10 per day (up to 90 days) begins. After six months, an additional penalty of 5% of the tax due or £300, whichever is greater, is charged. Interest on unpaid tax also accrues from 31 January regardless of the filing date.