UK Tax Consultancy That
Reduces Your Bill,
Not Just Files It

You must file a UK Self-Assessment return if you are self-employed with income over £1,000, a company director, a partner in a business partnership, have untaxed income (rental, overseas, savings) above relevant thresholds, earn over £100,000, have capital gains above the annual exempt amount, or receive child benefit while earning over £60,000. The online deadline is 31 January following the end of the relevant tax year (5 April). Late filing incurs an automatic £100 penalty, rising further the longer the delay. Sirius Global Solutions manages the entire process — gathering information, optimising allowances, and filing before the deadline.

The UK main corporation tax rate is 25% for companies with profits over £250,000, with a small profits rate of 19% for profits under £50,000 and marginal relief in between. Legitimate ways to reduce corporation tax include claiming the Annual Investment Allowance (up to £1 million) on qualifying plant and machinery, R&D tax relief for innovation activity, maximising pension contributions, using trading losses against past or future profits, and structuring remuneration tax-efficiently between salary and dividends. Sirius reviews your company's annual tax position to identify every available relief and ensure your CT600 is prepared to minimise liability within HMRC rules.

Rental income is taxable as part of your overall income. For residential properties, Section 24 means individual landlords can no longer deduct mortgage interest as an expense — instead a 20% basic rate credit applies against finance costs. Allowable deductions include letting agent fees, property management costs, maintenance and repairs (not improvements), insurance, and utilities paid by the landlord. Capital improvements are not revenue-deductible but reduce capital gains tax on eventual sale. Sirius provides comprehensive landlord tax advice including whether a limited company structure would be more tax-efficient given your portfolio size and personal income position.

UK residents are generally taxed on their worldwide income — including overseas employment income, foreign rental income, foreign dividends, and overseas pension income. Double taxation treaties (the UK has over 130) prevent paying full tax twice — relief is given by exemption or credit. UK resident non-domiciled individuals may use the remittance basis, under which foreign income and gains are only taxed if brought into the UK, though this involves giving up the personal allowance and CGT annual exempt amount where foreign income exceeds £2,000. Sirius provides expert advice on foreign income disclosure, treaty claims, and the most efficient approach for non-domiciled clients.

HMRC opens enquiries through both random selection and risk-targeting. Common triggers include significant income changes year-on-year, consistent losses, high expenses relative to turnover, lifestyle appearing inconsistent with declared income, discrepancies between your return and third-party data held by HMRC, and late or incorrect filings. HMRC may open an aspect enquiry or a full enquiry into your entire tax position. It is critical to engage a qualified tax advisor before responding to any HMRC letter. Sirius provides expert HMRC investigation support — reviewing your position, preparing a robust response, managing HMRC correspondence, and achieving the most favourable resolution available.

Yes — non-UK residents have significant UK tax obligations on UK-source income: UK rental income, UK employment income (for work done in the UK), UK pension income, and certain UK investment income. Non-resident landlords must operate the Non-Resident Landlord Scheme or register with HMRC to receive rents gross and file a Self-Assessment return. Non-residents must also report and pay capital gains tax on UK property disposals within 60 days of completion. Directors of UK companies may have UK tax on director's fees for UK duties. Sirius handles all UK non-resident tax filings and HMRC correspondence remotely — wherever in the world you are based.

IR35 (the off-payroll working rules) ensures contractors working through personal service companies who would be employees if engaged directly are taxed similarly to employees. Since April 2021, medium and large private sector clients (and all public sector clients) determine IR35 status via a Status Determination Statement. If inside IR35, income tax and NIC are deducted before payment to the PSC. Key factors HMRC considers include control, mutuality of obligation, substitution, and integration into the client's business. Sirius provides IR35 status reviews, contract analysis, and advice on structuring your engagement correctly to reflect the actual working relationship and minimise tax risk.

Legal tax planning uses UK tax law to structure activities most efficiently. Effective strategies include: combining salary, dividend, and pension contributions to minimise income tax and NIC; maximising the Annual Investment Allowance and capital allowances; claiming R&D tax credits for qualifying innovation; using EIS or SEIS investments for income tax and CGT reliefs; making pension contributions to reduce taxable profits; timing income and expenditure across accounting periods; planning property disposal timing around annual CGT exempt amounts; and for international businesses, using double taxation treaties and appropriate transfer pricing to minimise group-wide tax. Sirius conducts annual tax efficiency reviews to implement all available opportunities for legal tax reduction.