How to prepare clients for Self Assessment

Team Nomi

Sep 18, 2026
5 minutes read

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Self Assessment season becomes difficult when client information arrives late, records are incomplete, and accountants have to spend weeks chasing documents.

The solution is not simply to start preparing returns earlier. It is to build a clear client information and review process before the January rush.

For the 2025/26 tax year, the online Self Assessment deadline is 31 January 2027. But accountants do not need to make January the deadline for clients to provide their information.

Here is a practical approach to getting clients ready.

1. Start with a clear client checklist

Send clients a single clear list of the information you need, based on their circumstances.

This may include:

• • Employment income and P60/P45
  • Self-employment income and expenses
  • Property income and expenses
  • Interest and dividends
  • Pension income and contributions
  • Capital gains
  • Benefits and other taxable income
  • Student loan details
  • Gift Aid
  • Supporting documents

The checklist should reflect the client’s circumstances. A landlord does not need the same questions as a sole trader with employment income.

2. Set your own client deadline

The HMRC deadline is 31 January 2027, but your client deadline should be earlier.

For example, asking clients to provide their information by 30 November gives your team time to review records, chase missing details, prepare the return and get client approval before filing.

3. Use a tax questionnaire instead of long email chains

Long email chains can make it difficult to track what a client has provided and what is still missing.

Nomi’s Tax Questionnaire lets accountants send customised questions by email or through the mobile app. Completed information can then be imported into the client’s SA100 record.

This gives your team a consistent way to collect and review client information, particularly during a busy Self Assessment season.

4. Check HMRC information before chasing the client

Where available, review HMRC information before asking clients for documents they may not need to provide again.

Nomi can retrieve available HMRC information, including employment and pension data, and add it to the client’s Self Assessment record.

A simple process is:

Check existing data → request what’s missing → review the information.

5. Review records before preparing the return

Don’t rely on the questionnaire alone. Compare client responses with bookkeeping records, bank transactions and HMRC data where available.

Look for changes such as:

• • New income sources
  • Missing expenses
  • New property income
  • Dividends or capital gains
  • Significant changes from the previous year

For example, if a client reported rental income last year but doesn’t mention it this year, check whether the property is still generating income before preparing the return.

6. Prepare clients for MTD for Income Tax

Self Assessment preparation now needs to sit alongside MTD for Income Tax.

MTD started on 6 April 2026 for sole traders and landlords with qualifying income over £50,000. The threshold falls to over £30,000 from April 2027 and over £20,000 from April 2028.

Review your client list and identify:

Already in MTD → entering MTD next → needs a change in record keeping.

This helps you manage annual Self Assessment and ongoing MTD requirements within  the same client workflow.

7. Track outstanding information

As the number of returns grows, email and spreadsheets can make it harder to see which clients are ready to progress.

Track key stages such as:

Information requested → response received → documents outstanding → return prepared → client approval → filed

Nomi lets accountants track Tax Questionnaire responses and send reminders, helping teams manage outstanding client information more efficiently.

8. Build your Self Assessment process around exceptions

Not every client needs the same level of review.

Use a standard workflow for routine returns and give additional attention to clients with multiple income sources, property, capital gains, or other complexities.

Standard: Collect → check → prepare → approve → file

Complex: Collect → check → identify issues → request further information → review → prepare → approve → file

This keeps routine returns moving while giving your team more time for cases that require professional judgement.

A simple Self Assessment preparation checklist

Before starting a client’s return, check:

• • Client information is up to date
  • All income sources have been confirmed
  • Employment information is available
  • Property income has been checked, where relevant
  • Dividends and interest have been checked
  • Expenses and supporting records are available
  • HMRC information has been reviewed
  • Missing information has been requested
  • MTD status has been checked
  • Return has been reviewed before client approval

How Nomi can help accountants prepare Self Assessment clients

The most time-consuming part of Self Assessment is often not filing the return. It is getting the right information from the client in the first place.

Nomi brings several parts of the process together. Accountants can use digital tax questionnaires to collect client information, retrieve available HMRC data, track questionnaire responses, and connect Self Assessment with other Nomi modules.

That means your team can spend less time managing information requests and more time reviewing the tax position and dealing with client-specific issues.

Start your free trial of Nomi to see how it fits into your Self Assessment workflow.

Frequently asked questions

1. When should accountants start preparing clients for Self Assessment?

Ans. Start collecting client information several months before the 31 January deadline. This gives you time to review records, resolve queries, and file returns without a last-minute rush.

2. What information should accountants ask Self Assessment clients for?

Ans. It depends on the client’s circumstances but commonly includes employment income, self-employment income, property income, dividends, interest, pension information, capital gains, expenses, and other taxable income.

3. What is the Self Assessment deadline for 2025/26?

Ans. The online Self Assessment return and any tax due for the 2025/26 tax year are generally due by 31 January 2027.

4. Does MTD for Income Tax replace Self Assessment?

Ans.  No. Clients who are within MTD for Income Tax still need to submit a Self Assessment tax return for the relevant tax year. MTD adds digital record-keeping and periodic reporting requirements.

5. How can accountants reduce Self Assessment client chasing?

Ans. Start information collection early, use a structured questionnaire, set an internal deadline and track outstanding responses. Digital questionnaires and automated reminders can make this process easier to manage.