Plain-English HMRC Guides
Most people’s first contact with our team starts with the same question: “What does this letter actually mean?” This is where we answer that, in plain English, written by tax investigation specialists. Browse by situation below, or call us directly on 020 3827 1447 for confidential advice.
Code of Practice 9 (COP9)
HMRC suspects deliberate tax fraud. The CDF offers a route to settle without criminal prosecution, but only if handled correctly within 60 days.
VAT Investigations
From a routine compliance check to allegations of MTIC fraud, VAT enquiries can spiral fast. Understand what HMRC is looking for and how to protect your business.
Director Personal Liability
HMRC can pierce the corporate veil and pursue directors personally. Know your exposure, the defences available, and how to respond to a PLN.
Rental Property & Landlord Investigations
HMRC’s Let Property Campaign is ongoing. Undeclared rental income (from buy-to-let, holiday lets, Airbnb and overseas property) is one of HMRC’s highest-volume enquiry areas.
- Rental property investigation: full guide
- The Let Property Campaign explained
- What happens when HMRC finds undeclared income
- Top 10 landlord self-assessment errors
- Penalties for undeclared rental income
- FHL abolition: HMRC enquiries into historic claims
- The Non-Resident Landlord Scheme: withholding tax & penalties
- ATED: annual tax on enveloped dwellings
- Non-resident company landlords & CT
Stamp Duty Land Tax (SDLT) Enquiries
Multiple Dwellings Relief was abolished in 2024, but historic claims remain open to enquiry for years. Mixed-use claims involving gardens, paddocks and land are one of HMRC’s most actively litigated SDLT battlegrounds.
EIS & SEIS Tax Relief Clawback
EIS and SEIS relief stays conditional for years after it is claimed. A disqualifying event within the three-year holding period, investor connection, or a company-level failure can see HMRC claw it all back.
Private Residence Relief Challenges
Private Residence Relief can exempt an entire gain on a home sale, which is exactly why HMRC scrutinises claims where the quality or length of occupation looks doubtful.
Inheritance Tax: Business & Agricultural Relief
From 6 April 2026, 100% relief on business and agricultural property is capped at £2.5m combined. Above that threshold, trading status and valuation disputes now carry a direct tax cost, and HMRC investigations are rising accordingly.
Company Insolvency & HMRC
HMRC is now a preferential creditor in insolvency (since December 2020). Directors face disqualification, Personal Liability Notices, and winding-up petitions. Know the options before it’s too late.
Proceeds of Crime Act (POCA)
When HMRC tax investigations cross into suspected criminality, POCA proceedings can follow: account freezing orders, civil recovery, and unexplained wealth orders. Understand what’s at stake.
IR35 & Employment Status
IR35 and off-payroll working rules catch thousands of contractors and their engagers each year. HMRC’s CEST tool is not definitive, understand what actually determines status and how to protect your position.
- IR35 investigations: the full picture
- Off-payroll working rules (Chapter 10 ITEPA)
- HMRC’s CEST tool: what it gets wrong
- Defending an IR35 enquiry
- Status Determination Statements explained
- Mutuality of obligation & control: the real battleground
- Managed Service Company legislation explained
- Termination payments & PENP
- Salary sacrifice & OpRA
- Company car, van & fuel benefits
HMRC Discovery Assessments
HMRC can reopen tax years you thought were closed. Discovery assessments under s29 TMA 1970 have strict time limits and challengeable on “staleness” grounds, but only if you act quickly and correctly.
Schedule 36 Information Notices
HMRC has wide powers to demand documents and information. Schedule 36 FA 2008 notices carry serious penalties for non-compliance, but appeal rights exist and are often underused.
Offshore Assets & Worldwide Disclosure
HMRC receives automatic data on overseas accounts, investments and property from 100+ countries via CRS and FATCA. Undisclosed offshore income attracts penalties up to 200%. Understand your options before HMRC acts.
- Offshore assets investigation: full guide
- Import VAT, postponed accounting and the C79
- Customs post-clearance demands (C18)
- HMRC data-gathering powers: Schedule 23 and bulk data
- The Worldwide Disclosure Facility explained
- How HMRC gets your offshore data (CRS)
- Offshore penalties: how HMRC calculates them
- HMRC offshore nudge letters: what to do
- FIG regime compliance checks: the remittance basis replacement
- Non-resident CGT: the 60-day rule & penalties
- Statutory Residence Test enquiries: how HMRC challenges your status
Self-Assessment Enquiries
A routine compliance check can become a full enquiry into your affairs. HMRC has 12 months from your filing date to open one, and far longer if they discover errors. Know your rights and obligations from day one.
- Self-assessment enquiry: full guide
- How long HMRC has to open an enquiry
- HMRC compliance checks: what to expect
- Aspect vs full enquiry: the difference
- Forcing HMRC to close an enquiry
- What documents must you give HMRC?
- Best judgment assessments: missing or incomplete records
- Capital allowances: AIA, full expensing & SBA
- Pension annual allowance, taper & scheme pays
HMRC Criminal Investigation
When HMRC decides to investigate criminally rather than civilly, everything changes. Arrest, dawn raids, interviews under caution and prosecution, the stakes are completely different from a civil enquiry. Specialist advice is essential from the first moment.
Data Protection & Information Rights Against HMRC
You have a legal right to find out what HMRC holds on you, and to request general information about how it operates. Two different routes do two very different jobs, know which one you need.
Appeals, Reviews & HMRC Enforcement
Every appealable HMRC decision runs on the same clock: 30 days to appeal, 30 to accept a review, 45 for HMRC to complete it, 30 to reach the tribunal. Miss one and your options narrow sharply. And where a debt is established, HMRC can take it straight from your bank account.
- HMRC statutory review and the tax appeals ladder
- HMRC enforcement: goods, court orders and insolvency
- Direct Recovery of Debts: HMRC taking money from your bank account
- Late appeals: the Martland three-stage test
- Reasonable excuse: the Perrin four-stage test
- What happens at a tax tribunal hearing
- Payments on account and the self-assessment cycle
- Late payment penalties and interest
- HMRC determinations (s28C TMA): why you cannot appeal them
- Badges of trade: capital gain or trading income?
- Alternative Dispute Resolution in tax appeals: HMRC ADR explained
- Costs in tax tribunal appeals: when you can recover or be ordered to pay
- All case analyses →
HMRC Penalties & Challenges
HMRC issues millions of penalties every year. Many are successfully challenged on reasonable excuse grounds, through HMRC review or at the Tax Tribunal. Understanding the process is the first step to overturning an unjust charge.
How HMRC Finds Out: Data & Intelligence
HMRC’s Connect system cross-references data from over 30 sources, Land Registry, offshore bank reporting, letting platforms, card processors and more, before it even opens an investigation. Understanding what HMRC can see is the first step to managing your risk.
Disguised Remuneration & the Loan Charge
Tens of thousands of contractors and employees used disguised remuneration schemes. The 2019 loan charge brought the entire outstanding loan balance into tax in one year. If you are still affected, the options are time-sensitive.
R&D Tax Relief & Enquiries
HMRC now enquires into roughly one in five R&D claims. The competent professional test and contemporaneous evidence are usually where claims succeed or fail.
Construction Industry Scheme (CIS)
Losing gross payment status can cripple cash flow overnight. From April 2026 HMRC also gains a fraud-connection cancellation power with a five-year reapplication bar.
Reasonable Adjustments in HMRC Investigations
The Equality Act 2010 duty to make reasonable adjustments applies to HMRC as much as any public body, and runs alongside, not instead of, a tribunal’s own procedural adjustment powers.
Trust Registration Service
Non-registration carries a £5,000 penalty per trust, with a separate regime for trusts that are also Reporting Financial Institutions. HMRC has shown tolerance for prompt, voluntary correction.
SEIS for Individual Investors & Small Companies
SEIS gives the most generous income tax relief in the UK system, but the conditions stay live for three years after investment and can be broken by either the company or the investor.
FOS Complaints & Consumer Credit Disputes
A free alternative to court for disputes with banks, lenders and credit providers, but eligibility, timing and process all have to be got right.
Credit Reference Agencies & CIFAS Markers
A wrong entry on a standard credit file and a CIFAS fraud marker are different problems with different legal routes, and litigating a CIFAS challenge badly carries real risk.
Digital Platform Reporting & the Side Hustle Economy
From January 2026 platforms such as eBay, Vinted, Airbnb and Uber report seller and host earnings directly to HMRC under the OECD Model Rules. The £1,000 trading allowance and the platform thresholds do not always line up.
High Income Child Benefit Charge (HICBC)
The £60,000–£80,000 taper catches thousands of taxpayers who never realised they owed anything until an HMRC enquiry or nudge letter arrived. A new PAYE payment option from October 2025 changes how the charge is settled.
EMI Share Options
Enterprise Management Incentive options offer generous tax treatment, but a single qualifying-condition slip can turn a tax-advantaged exercise into an unapproved one. The scheme limits expand significantly from 6 April 2026.
Inheritance Tax on Unused Pension Funds
Finance Act 2026 brings most unused pension funds and death benefits into the taxable estate from 6 April 2027, a change HMRC estimates will draw an extra 10,500 estates into Inheritance Tax every year.
Employee Ownership Trusts
The Autumn Budget 2025 halved the headline Capital Gains Tax relief on a qualifying sale to an EOT, while adding new trustee residency and independence conditions that run for four years after the sale.
Basis Period Reform
Sole traders and partnerships moved onto the tax year basis from 2024/25. Transition profit is still being spread through to 2027/28, and 2025/26 is the last chance to use any unclaimed overlap relief.
Free Tools
Try our free calculators and software, the same models we use to estimate exposure when clients first call us.
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