Tax Investigations & Appeal London
Expert CIS Accounting & Compliance in
London & United Kingdom (UK)
Specialist Tax Support for Contractors and Subcontractors.
Navigating the Construction Industry Scheme (CIS) is business-critical for any firm operating in the UK building sector. At Acumen Accountants & Tax Advisor (AcumenAGC), we ensure your business remains fully compliant with HMRC regulations, helping you avoid heavy penalties and optimize your cash flow. Whether you are a large developer in the City or a specialist subcontractor in Southwark, we provide the technical expertise to manage your CIS obligations seamlessly.
HMRC CIS Compliance
Accurate monthly CIS300 returns filed on time, every time.
Subcontractor Verification
Instant status checks to ensure correct 20% or 30% deductions.
Tax Refund Specialists
We help subcontractors reclaim overpaid tax quickly and efficiently.
Fixed-Fee Certainty
No hidden costs during a stressful time.
Service Overview
Professional CIS Support
The Construction Industry Scheme (CIS) is a specific HMRC tax framework where contractors deduct money from a subcontractor’s payments and pass it to HMRC as advance tax and National Insurance payments.
Compliance is mandatory for all construction businesses, but also for “deemed contractors”—organisations that do not do construction work but have a high annual spend on building projects. With HMRC’s powers increasing from 6 April 2026, particularly regarding Gross Payment Status (GPS) and fraud prevention, professional oversight is no longer optional—it is a necessity for business continuity.
Who needs it?
Our CIS specialists for UK limited companies and sole traders support:
- Main Contractors
- Main Contractors
- Property Developers
- Deemed Contractors
100%
UK GAAP & IFRS Compliance
Who This Service Is For
Tailored Wealth Protection for Every Goal
Our London audit team tailors every review to your specific industry requirements.
Main Contractors
Managing large-scale supply chains and high-volume monthly returns.
Subcontractors
Individuals and companies needing accurate deduction statements and year-end tax reclaims.
Property Developers
Handling the complexities of site preparation, alterations, and repairs.
Deemed Contractors
Businesses (like housing associations or large retailers) spending over £3 million on construction in 12 months.
Landlords
Addressing undisclosed rental income and Capital Gains Tax enquiries.
10+
Years of Experience
500+
Audits Completed
98%
Client Retention
24h
Response Time
Why Choose AcumenAGC
London’s Leading accountants for tax investigations
As a leading professional CIS firm in London, we combine local knowledge with national reach.
- HMRC Expertise: We manage your HMRC CIS Gateway directly, ensuring all filings meet current UK tax laws.
- Compliance-First Approach: We mitigate the risk of losing your Gross Payment Status by maintaining a spotless filing history.
- Affordable CIS for UK Businesses: Transparent, fixed price CIS London UK services that scale with your project size.
- Dedicated Accountant: You will work with a specialist who understands the unique financial landscape of the UK construction industry.
OUR PROCESS
Our 5-Step CIS Compliance Process
We use a streamlined, tech-enabled approach to minimize disruption to your daily operations.
Step 01
Registration & Setup
We register your business with HMRC as a contractor, subcontractor, or both.
Step 02
Verification
Before you pay a new subcontractor, we verify their tax status via the HMRC portal to determine if a 20%, 30%, or 0% (Gross) deduction applies.
Step 03
Monthly Processing
We calculate precise deductions, excluding materials and VAT, to ensure your payments are legally sound.
Step 04
CIS300 Filing:
We submit your monthly return to HMRC by the 19th of every month.
Step 05
Deduction Statements
We provide your subcontractors with the legal statements they need to account for their tax.
FAQ
CIS Frequently Asked Questions
What is the deadline for CIS monthly returns?
You must send your monthly return (Form CIS300) to HMRC by the 19th of every month following the end of the tax month. For example, if you are reporting payments made between 6 May and 5 June, the return must reach HMRC by 19 June.
What are the CIS deduction rates for 2026?
The standard rate for registered subcontractors is 20%. For unverified or unregistered subcontractors, the higher rate of 30% applies. Subcontractors with Gross Payment Status receive payments with 0% deducted.
What changes are coming to CIS in April 2026?
From April 2026, HMRC is introducing stricter “knew or should have known” fraud rules. Businesses connected to fraudulent supply chains risk immediate removal of their Gross Payment Status for five years and penalties of up to 30%.
Can I get a CIS tax refund?
Yes. Many subcontractors find they have overpaid tax because the 20% deduction is taken from their gross turnover (excluding materials). We specialize in reclaiming CIS tax overpayments through your annual Self-Assessment or Corporation Tax return.
Do you offer HMRC compliant services for businesses outside London?
Absolutely. While we are a best tax investigation firm in London for small businesses, our cloud-based systems allow us to serve any UK-registered business or resident.
Our Locations
Expert Tax Investigations & Appeals Specialist in the Heart of London
Based in the heart of the capital, we serve clients across all London boroughs, from the financial hub of the City of London and Canary Wharf to the thriving tech scenes in Shoreditch and Camden.
Canary Wharf &
Docklands (E14)
Westminster & Central London
The City of London (The Square Mile)
Camden, Islington & North London
Canary Wharf HQ
London, UK
Protect Your Business Today
Don’t face HMRC alone. Professional representation is the most effective way to ensure a fair outcome and minimize potential liabilities.
Book a confidential consultation with an AcumenAGC specialist. We respond to all enquiries within 24 business hours.