The best self assessment help for accountants starts with HMRC’s Tax Agent’s Handbook, then the section-by-section Self Assessment guidance on GOV.UK. After that, look at HMRC-recognised software and professional body support. Add Making Tax Digital preparation, as it affects many self-employed and landlord clients from April 2026.
At a glance
- HMRC’s Tax Agent’s Handbook is the official starting point for agents, covering acting for clients, using HMRC services and contacting HMRC.
- GOV.UK’s Self Assessment help collection has a guide for each return section: employment, self-employment, partnership, property, foreign income, capital gains, pensions and more.
- HMRC publishes an official list of commercial software suppliers that can submit Self Assessment returns.
- HMRC’s MTD guidance for agents says to set up an agent services account, choose MTD-compatible software and sign up clients.
- Chati has been developing apps since 2009 and trains its chatbot on each customer’s own data.
Where can accountants get help with Self Assessment?
There are five main sources: HMRC’s agent guidance, the return-section guidance on GOV.UK, approved software, professional bodies and the Making Tax Digital (MTD) resources for agents. Used together, they cover almost every question a practice will meet in a filing season.
- HMRC agent guidance: explains how to act for clients and deal with HMRC.
- Return-section guidance: tells you what each part of the return asks for.
- Software: prepares and submits returns in a format HMRC accepts.
- Professional bodies: offer technical support, bulletins and training.
- MTD resources: set out the steps for getting your practice and clients ready.
Which source suits which practice?
A sole practitioner will probably lean on GOV.UK and a single software package. That keeps the process light. A growing practice needs more: shared reference material, bulk filing and a clear routine for onboarding clients. Someone newly qualified will get the most from the Tax Agent’s Handbook and the return-section guides, plus the technical helplines run by their professional body.
One rule applies to everyone. Tax-year details such as dates, rates and thresholds change, so check them against GOV.UK before you file anything.
What does HMRC’s Tax Agent’s Handbook cover?
The Tax Agent’s Handbook is HMRC’s own starting point for agents. It helps you find guidance, use HMRC services and get in touch with HMRC.
Acting for clients
It points you to how client authorisation works and what you need before you can act on someone’s behalf. Getting this right at the start of an engagement saves delays later, when a client’s records are needed in a hurry.
Helplines, compliance and penalties
The handbook also helps you find the right route to HMRC for agent queries, along with guidance on compliance and penalties. Treat it as a pointer to the current rules rather than a summary of them, and follow the links through to the detail for the year in question.
How to use it
Do not try to read it end to end. Bookmark it, share it with your team and go back to it when a specific question comes up, such as how to authorise a new client or who to call about a problem. That makes it a practice reference rather than a reading list.
Where can I find guidance for each part of the Self Assessment return?
GOV.UK groups its guidance by return section, and everything sits in one place: the Get help filling in your Self Assessment tax return collection. Open the guide for the section you are working on and read it alongside the client’s records.
| Return section | What to check |
|---|---|
| Employment | Income and benefits shown on the client’s documents, and any expenses claimed |
| Self-employment | Income, allowable expenses and which accounting basis applies |
| Partnership | Share of profit and whether the partnership return has been dealt with |
| UK property | Rental income, costs and whether joint ownership is handled correctly |
| Foreign income | Source of income, any tax already paid abroad and the records held |
| Capital gains | Disposals, acquisition costs and dates |
| Pensions | Contributions, payments received and any relief claimed |
| Other UK income | Interest, dividends and any other taxable income |
| Charitable giving | Gift Aid donations and records of what was given |
| Reliefs | Which reliefs the client claims and the evidence for each |
| Student loans | Whether repayments are due and how they are collected |
| Trusts and estates | The client’s role and the income that comes through |
Common problem areas in client files
Missing paperwork tends to cause the most trouble: gaps in property costs, unclear self-employed expenses and disposal records for capital gains. Ask for these early rather than in the final week before a deadline.
Look at the update date on each guidance page before you rely on it. A page you bookmarked last year may have changed.
Which software can agents use to file Self Assessment returns?
HMRC publishes a list of commercial software suppliers whose products can submit valid Self Assessment returns, and accountants should choose from that list. You will find it on GOV.UK under Self Assessment commercial software suppliers.
The list is long and it changes, so we link to it rather than copy it here. Check it directly when you are choosing or renewing a package.
What to compare
- Cost: per-return pricing or a flat subscription, and what happens as your client list grows.
- Client portal: a simple way for clients to upload documents and approve returns.
- Bulk filing: useful once you handle many returns at the same time.
- MTD support: whether the product is, or will be, compatible with Making Tax Digital for Income Tax.
- Integrations: links to your bookkeeping, practice management and document tools.
Cloud or desktop?
In general terms, cloud accounting packages make it easier to share records with clients and see their figures through the year. Desktop tax packages can suit practices that prefer to work on a fixed set of tools in-house. Many firms use a mix. We do not rank products here, because the right fit depends on your client base and how you work.
What do accountants need to know about Making Tax Digital for Income Tax?
HMRC’s agent guidance sets out three steps. Set up an agent services account, choose MTD-compatible software and sign up your clients. The full detail is on HMRC’s Making Tax Digital for accountants, bookkeepers and agents page.
Thresholds and dates
MTD for Income Tax is being brought in in stages, based on a client’s income. The thresholds and start dates depend on the level of combined self-employment and property turnover, and later stages will change the picture. Confirm the current thresholds and start dates on GOV.UK before you advise any client.
Conversations to have now
- Which clients are likely to be affected, and when.
- How they keep records today, and whether that needs to change.
- Who will submit updates, and what your fee will cover.
A short readiness checklist
- Set up your agent services account.
- Choose software that supports MTD.
- List clients who may fall in scope and note their likely start dates.
- Agree record-keeping habits with each affected client.
- Sign up clients as HMRC’s agent guidance describes.
How can accountants cut repeat client questions in Self Assessment season?
Most busy-season queries are repeats: deadlines, which documents to send and what your fees are. A website chatbot can answer those from your own pages, which leaves your team free for work that needs a qualified person.
Chati is an AI chatbot that answers customers from a business’s own website. It shows the sources it used, and it hands the chat to your human team when it is unsure. It supports your practice and does not replace professional advice.
Lead capture and bookings
New clients often make contact late in the season. Chati can capture their details and take bookings, so an enquiry made in the evening is waiting for you the next morning. You can also brand the chatbot to match your site.
Trained on your data
Chati offers custom integration and is trained on the customer’s own data, so its answers reflect what your firm actually says. We’ve been developing apps since 2009. Our customers choose us for great value for money. To see how it works, read our how it works page or look at our pricing.
As ever, a chatbot is only as good as the pages behind it. Keep your deadline, document and fee pages clear and up to date.
What help is there for clients who cannot afford an accountant?
Charities such as TaxAid run free helplines and guides for people who cannot get paid advice, so accountants can point those clients there. TaxAid’s page I need help with tax explains what is on offer.
When to refer
Consider a referral when a person’s circumstances mean they cannot reasonably pay your fees, or when their query falls outside what your practice does. Be kind about it. Explain plainly that you cannot take the work on and give them the details of where to go, so they do not leave empty-handed.
Signposting on your website
A short section on your site that names free sources of help costs you little. It saves time for your team, and it shows visitors that you want them to find the right support, even when it is not with you.
How do accountants keep Self Assessment knowledge up to date?
Use a simple routine: check GOV.UK update dates, follow your professional body’s bulletins and review agent guidance at the start of each tax year. Small, regular checks beat a rush of reading in January.
Professional body support
Most professional bodies offer technical support, newsletters and training for members. Use them. They are a good place to ask about unusual cases, and they often flag changes before many practices have noticed.
An annual pre-season review
Before the season starts, go through your engagement letters, checklists and website pages. Update deadlines and thresholds against GOV.UK, and check that your software is current. It is also a good time to look again at the Tax Agent’s Handbook for anything that affects how you work.
Who to contact at HMRC
For agent issues, start with the contact routes signposted through the Tax Agent’s Handbook rather than relying on old phone numbers or notes. Contact details can change.
If repeat client questions are eating into your busy season, get in touch with Chati and we will show you how a chatbot trained on your own website could help.
Frequently asked questions
When is the Self Assessment deadline for online returns?
Deadlines depend on the tax year, so check the current dates on GOV.UK before advising clients. Also look at the guidance on penalties for late filing and payment.
How do I authorise an agent to file Self Assessment for a client?
The client must authorise you before you can act for them. You should follow the steps linked from the Tax Agent’s Handbook, which points to the current process.
Is there an HMRC helpline for tax agents?
Yes, HMRC has contact routes for agents. The best place to find the current details is the Tax Agent’s Handbook, as numbers and opening times can change.
Do accountants need MTD-compatible software?
For Making Tax Digital for Income Tax, HMRC’s agent guidance tells you to choose MTD-compatible software. Check current start dates and thresholds on GOV.UK to see when it applies to your clients.
Can a chatbot answer Self Assessment questions for clients?
A chatbot can answer common questions, such as deadlines, documents and fees, from your own website content. It should not replace professional advice, and Chati hands chats to your team when it is unsure.
Where can clients get free Self Assessment help?
Clients who cannot afford an accountant can try TaxAid, which offers free helplines and guides. GOV.UK also has guidance for each section of the return.
