Self-assessment is required if you're:
From April 2026, Making Tax Digital for Income Tax also applies to sole traders and landlords with income over £50,000, requiring quarterly digital updates. Missing the self-assessment deadline results in automatic £100 penalties, with further penalties for continued delays. Let us ensure your return is accurate and submitted on time.
Important dates to remember for the 2026/27 tax year
Register for self-assessment if you need to complete a tax return for the previous tax year
Submit paper tax returns by this date (we recommend online submission)
Deadline for online tax return submission and payment of tax owed
Second advance payment towards next year's tax bill (if applicable)
Professional self-assessment services from start to finish
We handle all aspects of your self-assessment return from start to finish
Identify all eligible reliefs and allowances to minimise your tax bill
Never miss a deadline - we submit your return well before the 31 January cutoff
Comprehensive self-assessment service
Complete self-assessment tax return preparation
Maximisation of allowances and tax reliefs
Capital gains tax calculations and reporting
Rental income and property tax advice
Partnership and dividend income reporting
HMRC submission and confirmation handling
Claiming all eligible expenses and allowances to reduce your tax bill
Avoid costly errors that trigger HMRC investigations
Automatic penalties and interest
Failing to declare all income sources including freelance work, rental income, foreign income, or investment returns can result in £3,000+ penalties plus interest.
Tax bill adjustment and penalties
Claiming personal expenses as business costs, or overclaiming without proper receipts, triggers HMRC enquiries and potential fraud investigations.
£100 immediate penalty
Missing the January 31st deadline results in automatic £100 fine, with additional daily penalties of £10 accumulating after 3 months.
Underpaid tax and interest
Not reporting asset sales or incorrectly calculating gains leads to significant tax underpayments, with HMRC able to review 6 years of returns.
Overpaying tax unnecessarily
Failing to claim foreign tax credit relief on overseas income means paying tax twice - both abroad and in the UK on the same income.
Missing £252 annual saving
Not transferring unused personal allowance between spouses wastes valuable tax relief worth up to £252 per year for eligible couples.
All our self assessment packages come at a fixed fee agreed up front after a free consultation — never an hourly rate. Your price is based on your turnover, transaction volume and the services you need, so you always know exactly what you're paying. Every package includes full SA100 preparation, all allowances and reliefs claimed, HMRC submission before the 31 January deadline, unlimited email support, and a dedicated ACCA-qualified accountant.
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Real feedback from businesses we've helped succeed
"1st Accountants transformed our tax management. Their MTD expertise saved us thousands and gave us peace of mind. Highly professional service!"
Sarah Mitchell
Tech Startup Ltd
Filing a self assessment return is more than copying figures into HMRC software. It is an opportunity to claim every allowance you are entitled to and to make sure your tax is correct to the penny. Our accountants prepare the return for you, check it against your records and file it well before the 31 January deadline.
For sole traders, landlords and directors alike, we combine the return with practical advice on paying the right amount on account, avoiding penalties and keeping better records for next year.
We make sure you know exactly what you owe and when it is due, including any payments on account. No last-minute panic in January, no avoidable fines, and no over-paying because a claim was missed.