Self Assessment
Services
A Self Assessment tax return tells HMRC what you earned outside PAYE and works out what you owe. You'll need to file one if you were self-employed and turned over more than £1,000, received rental income, drew dividends from your own company, made a capital gain, or earned over £50,000 while claiming Child Benefit. We prepare and file the return, tell you exactly what to pay and when, and make sure you've claimed everything you're entitled to.
Self Assessment — what it is and who needs it
A Self Assessment tax return tells HMRC what you earned outside PAYE and works out what you owe. You'll need to file one if you were self-employed and turned over more than £1,000, received rental income, drew dividends from your own company, made a capital gain, or earned over £50,000 while claiming Child Benefit. We prepare and file the return, tell you exactly what to pay and when, and make sure you've claimed everything you're entitled to.
Most people who come to us have been doing it themselves and are not certain they've got it right. That's a reasonable worry: the most common mistakes we see are missed allowable expenses, forgetting pension contributions and Gift Aid (both of which extend your basic rate band), not claiming the trading allowance where it beats itemised expenses, and misreporting dividend income. None of these get flagged by HMRC's online form — it accepts whatever you type.
Our process is deliberately unexciting. You send us your figures, we ask questions about anything that looks unusual, we prepare the return and send it to you with a plain-English summary of what you owe and why. Nothing is filed until you've approved it. You'll know your January payment figure well before Christmas, which is the whole point.
The filing deadline for an online return is 31 January following the end of the tax year, with payment due the same day and a payment on account for the following year often due alongside it. If your bill is over £1,000 you'll usually be asked for two payments on account, each 50% of the previous year's liability — a nasty surprise in a first profitable year if nobody warned you. We warn you.
Who this is for
Sole traders, landlords, company directors taking dividends, people with side income alongside a salary, and anyone who has received a notice to file from HMRC.
Key facts & deadlines
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HMRC deadline
Online: 31 January. Paper: 31 October.
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Who must file
Self-employed, landlords, directors, higher-rate taxpayers, anyone with untaxed income over £1,000.
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Late filing penalty
Automatic £100 — rising to £900+ after 6 months, plus interest on unpaid tax.
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Personal allowance
£12,570 (2025/26). Unused allowance cannot be carried forward.
Free consultation — no obligation
Everything included in our
Self Assessment service
Our all-inclusive service means no surprises — everything you need is handled by your dedicated accountant.
- Full preparation of your SA100 and supplementary pages
- Review of allowable expenses and reliefs
- Capital gains calculations where needed
- Dividend and savings income reporting
- Checking your tax code for PAYE income
- Filing online with HMRC once you approve
- A clear statement of what to pay and when
- Reminders ahead of the January and July deadlines
Who our Self Assessment
service is designed for
Sole traders, landlords, company directors taking dividends, people with side income alongside a salary, and anyone who has received a notice to file from HMRC.
Quick checklist
- Full preparation of your SA100 and supplementary pages
- Review of allowable expenses and reliefs
- Capital gains calculations where needed
- Dividend and savings income reporting
- Checking your tax code for PAYE income
- Filing online with HMRC once you approve
- A clear statement of what to pay and when
- Reminders ahead of the January and July deadlines
TAG Accountancy vs. going it alone
See exactly what you get when an expert handles your self assessment.
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How our Self Assessment service works
We keep it simple. No jargon, no chasing — just a reliable service that runs in the background.
Send us your figures
Income, expenses, and anything unusual from the year. If your bookkeeping is with us it's already done.
We prepare and check
We build the return, query anything that looks off, and look for reliefs you haven't claimed.
You approve, we file
You get a plain-English summary and the figure to pay. Nothing goes to HMRC until you say yes.
Common Self Assessment questions — answered
Can't find the answer you need? Ask us directly →
An online return for the tax year ending 5 April must be filed by 31 January the following year, and any tax owed is due the same day. Paper returns are due earlier, by 31 October. If you also make payments on account, the second one falls due on 31 July.
We aim to have returns finished well before Christmas so you know your January figure in good time.
You generally need to file if you were self-employed with turnover over £1,000, received rental income, are a company director taking dividends, made a capital gain above the annual exempt amount, or earned over £50,000 while you or your partner claimed Child Benefit.
If you have had a notice to file from HMRC you must submit a return even if you owe nothing, until HMRC withdraws the notice. If you are not sure, ask us — it takes five minutes to check.
There is an automatic £100 penalty the day after the deadline, even if you owe no tax. After three months it becomes £10 a day up to £900, and further penalties apply at six and twelve months. Interest runs on unpaid tax from the due date.
If you are already late, file as soon as possible — the penalties stack up rather than replacing each other.
Anything incurred wholly and exclusively for the business. For most sole traders that covers stock and materials, tools and equipment, business insurance, accountancy fees, business travel and mileage, phone and internet on the business proportion, and a reasonable amount for working from home.
What you cannot claim is ordinary commuting, client entertaining, or the personal share of anything you use for both business and private purposes. We go through this with you rather than guessing.
Ready to simplify your
Self Assessment?
Join 250+ businesses who trust TAG Accountancy to handle it brilliantly. The first consultation is completely free.
Let's talk about
your business.
Whether you want to switch accountant, need help with a specific return, or just want to know how much you could be saving — get in touch. The first call is always free.
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01603 559824
Email Us
office@tag-accountancy.co.uk
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5 Marlingford Road, Bawburgh
Norwich, NR9 3LU
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