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UK Tax Diary August/September 2026

1 August 2026 – Due date for Corporation Tax due for the year ended 31 October 2025.

7 August 2026 – Making Tax Digital (MTD) for Income Tax first quarterly update deadline for self-employed individuals and landlords mandated to comply with MTD. This quarterly update covers the period 6 April 2026 to 5 July 2026.

7 August 2026 – VAT Return and Payment Deadline for businesses submitting quarterly VAT Returns with a VAT period ending 30 June 2026. Returns must be submitted and any VAT due paid electronically by this date.

19 August 2026 – PAYE and NIC deductions due for the month ended 5 August 2026. (If you pay electronically, the due date is 22 August 2026.)

19 August 2026 – Filing deadline for the CIS300 monthly return for the month ended 5 August 2026.

19 August 2026 – CIS tax deducted for the month ended 5 August 2026 is payable by today.

1 September 2026 – Due date for Corporation Tax due for the year ended 30 November 2025.

19 September 2026 – PAYE and NIC deductions due for the month ended 5 September 2026. (If you pay electronically, the due date is 22 September 2026.)

19 September 2026 – Filing deadline for the CIS300 monthly return for the month ended 5 September 2026.

19 September 2026 – CIS tax deducted for the month ended 5 September 2026 is payable by today.

Source:HM Revenue & Customs | 07-07-2026
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Aitch
I'm Aitch, the Founder and CEO of CIGMA Accounting Ltd. As a Chartered Management Accountant and as a CIMA member, I've spent more than 16 years helping businesses, entrepreneurs, landlords, and individuals with tax planning, accounting, and HMRC compliance. As a chartered accountant in London, I'm passionate about making complex tax matters easier to understand and helping clients make confident financial decisions. Over the years, I've advised start-ups, SMEs, established companies, and high-net-worth individuals across a wide range of tax and accounting matters. My expertise includes Corporation Tax, Self-Assessment, Capital Gains Tax, Inheritance Tax planning, R&D tax relief, capital allowances, international tax, and resolving complex HMRC compliance issues. Whether clients need a business accountant, tax accountant, or strategic tax advisor, my focus is always on delivering practical advice that creates long-term value. One of my specialist areas is Making Tax Digital (MTD). I've worked extensively with businesses preparing HMRC's digital reporting requirements, helping them move to cloud accounting, improve financial processes, and adopt technology that makes compliance more efficient. I regularly speak at Making Tax Digital roadshows, industry events, and educational sessions in collaboration with Zoho Books, sharing practical insights into digital accounting, tax legislation, and the future of the profession. Many business owners looking for the best accounting firm in London are not simply searching for an accountant they're looking for trusted advice, responsive support, and long-term value. That's the approach I've taken in building CIGMA Accounting. My team and I work closely with businesses across London and the UK, providing accounting services, tax advisory, bookkeeping, payroll, VAT, company accounts, and strategic tax planning tailored to each client's goals. Through this website, I share practical guidance on UK taxation, Making Tax Digital, HMRC updates, Corporation Tax, Self-Assessment, and business finance. My aim is to provide reliable, straightforward information that helps business owners understand changing regulations, reduce compliance risks, and make informed financial decisions with confidence.