Self-assessment tax return help for complex personal tax affairs

A paper return must reach HMRC by 31 October 2026. An online return, and any tax you owe, must be filed and paid by 31 January 2027. If you want HMRC to collect a small balance through your tax code, the online return must be in by 30 December 2026. If you have not registered for the year and need to, the 5 October 2026 registration date has passed, so act now.

A return is complicated when the answer depends on judgement rather than just entering figures. That includes overseas income or assets, rental property, share and crypto disposals, a move into or out of the UK, trusts, company shareholdings and income close to a threshold such as £100,000. These are the returns where a small misunderstanding can change the tax by a surprising amount.

Usually yes, if you are UK resident and the income is not already fully taxed and reported through other means. Overseas interest, rent, dividends, pensions and employment income generally go on the foreign pages of the return, and double tax relief may reduce the UK bill. Even income taxed abroad often needs to be declared. The detail depends on your residence, so we check that first.

Because your residence status for the year decides which pages you complete and what the UK can tax. A UK resident reports worldwide income and gains, while a non-resident reports mainly UK income. In the year of a move, split-year treatment can divide the year. The return asks you to state your residence position, and HMRC checks it, so we settle it before the figures.

A late return brings an immediate £100 penalty. After three months, daily penalties of £10 can build up to a maximum of £900. At six months and twelve months there are further penalties of 5% of the tax due or £300, whichever is greater. Late payment also attracts 5% penalties at 30 days, six months and twelve months, plus interest. File as soon as you can, even if the figures are estimates.

Yes. HMRC can open an enquiry into a return within 12 months of the day it was filed, or later if it finds that tax was missed. The time limits for assessing extra tax run to four years, six years for carelessness, and 20 years for deliberate behaviour, with a 12-year limit for some offshore matters. Accuracy at the filing stage is the best protection.

They are advance payments towards next year's bill, each equal to half of last year's tax, due on 31 January and 31 July. They apply unless your last bill was under £1,000, or you paid more than 80% of your tax through your tax code or deduction at source. After a one-off gain or a drop in income, you can ask to reduce them, but an overly optimistic reduction brings interest.

Yes, if you sold assets and your gains are above the annual exempt amount, or total proceeds were above the HMRC reporting threshold, you generally need to report them. Residential property gains also need a separate 60-day report. Crypto disposals have their own section of the return. The calculation uses pooled costs and special matching rules, so records matter.

Rental income and allowable expenses go on the UK property pages, with finance costs given a basic-rate tax reduction rather than a full deduction. Joint ownership, jointly owned income splits and capital gains on sale add complexity. From 6 April 2026 Making Tax Digital for Income Tax is mandatory for people with qualifying income over £50,000. We help with the return and the planning behind it.

We can prepare and file it, but we are not designed to be a low-cost filing service for simple cases. Our value is in returns where the position needs judgement: overseas income, gains, property, residence changes and crypto. If your return is simple, an accountant or the HMRC online service may serve you better, and we will say so on the first call.

You can usually amend a return online within 12 months of the 31 January filing deadline. After that, you can write to HMRC to correct an error. Telling HMRC before they find the problem normally leads to much lower penalties than being found out. Where offshore income or large amounts are involved, we assess the position carefully before contacting HMRC.

If you or your partner receives child benefit and either of you has adjusted net income above £60,000, an extra tax charge applies. It builds at 1% of the benefit for every £200 over £60,000 and equals the full benefit at £80,000. The higher earner pays it through the return. Pension contributions or gift aid donations can reduce adjusted net income and the charge.

Keep every document that supports a figure: bank and broker statements, contract notes, property purchase and sale papers, rental accounts, foreign tax certificates and residence evidence such as a travel diary. Keep them for long enough to cover HMRC's ability to look back, which for some years and some offshore matters is far longer than the usual four. A digital folder per tax year works well.

You complete the main return plus the residence pages, stating whether you are resident, non-resident or entitled to split-year treatment. If split-year applies, income and gains from the overseas part of the year may fall outside UK tax. UK-source income such as rent usually remains taxable. The dates of your departure and the nature of your accommodation are central, so keep proof.

Often yes, if you have other income or gains. PAYE covers your salary, but a return may be needed for untaxed income, self-employment profits, rental profit, gains above the allowance, high income child benefit charge, or foreign income. If HMRC has asked you to file, you must, even when you think everything is taxed already.

Well before the January deadline. Overseas statements, tax certificates and valuations take time to collect, and decisions such as residence or the treatment of a disposal can affect planning you could have done before 5 April. We encourage clients to speak to us in the tax year, not after it ends. Starting in the autumn leaves time to resolve issues without pressure.