Tax Investigation Specialists in London
An HMRC letter opening a compliance check rarely arrives at a convenient time, and how you respond in the first few weeks often shapes how the whole case unfolds. HMRC has wide powers, firm deadlines, and penalties that scale sharply with how the case is handled.
Whether it's a routine check of a single Self Assessment return or a serious fraud investigation under Code of Practice 9, experienced representation from the first letter onward is the difference between a check that closes quietly and one that escalates.
The Finance Equation Ltd is an award-winning, ACCA-regulated firm of chartered certified accountants with over 30 years' experience, representing individuals and businesses across London through HMRC compliance checks and investigations — managing the process on your behalf, so you're never explaining yourself to HMRC alone. It's one part of our wider taxation services, alongside personal tax, property tax, company taxation and tax planning.
What Triggers an HMRC Compliance Check
HMRC opens compliance checks to confirm you're paying the right amount of tax, and a check can examine any tax you pay. A check can follow a pattern HMRC's systems have flagged, information reported by a third party, or simply routine review — the reason isn't always made clear at the outset, which is exactly why an early, accurate response matters.
A check into your Self Assessment return or your Company Tax Return follows the same underlying rules — including HMRC campaigns aimed specifically at landlords, such as the Let Property Campaign, which touches many of our property tax clients directly.
Accurate records, prepared and reviewed before HMRC ever asks to see them.
What Happens During a Compliance Check
HMRC will contact you in writing or by phone to explain what they're checking, and may ask to visit your home, your business premises, or your adviser's office.
HMRC opens the check
Contact by letter or phone, explaining what's being checked. You're entitled to have an accountant or legal adviser present throughout.
Information is reviewed
We manage correspondence and prepare what's requested accurately and on time — making sure nothing is volunteered that doesn't need to be.
The check closes
HMRC confirms your figures, repays overpaid tax with interest, or asks for additional tax — usually within 30 days, plus interest and any penalty due.
If you disagree with how HMRC is handling the check, Alternative Dispute Resolution is available before matters go further — see the general information on HMRC's compliance checks for the full process.
Serious and Suspected Fraud: Code of Practice 8 and 9
Where HMRC's Fraud Investigation Service becomes involved, the case is handled very differently.
Specialist investigations
Covers serious matters, including bespoke tax avoidance, that fall short of suspected fraud.
Suspected deliberate fraud
Handled through the Contractual Disclosure Facility — HMRC agrees not to pursue a criminal investigation into the fraud disclosed, in exchange for a complete and honest account.
Accepting a CDF offer means submitting an outline disclosure within 60 days, followed by a full formal disclosure, and remaining liable for the tax, interest and civil penalties due, though genuine cooperation can reduce those penalties. Rejecting the offer, or making an incomplete disclosure, removes that protection and leaves HMRC free to investigate independently — including, potentially, as a criminal matter. Getting specialist advice before responding to a Code of Practice 9 letter isn't optional; it's the single decision that determines whether the case stays civil.
The Cost of Getting It Wrong: Penalties for Inaccuracies
When HMRC identifies an error, the penalty charged depends on why it happened — on top of the tax and interest owed.
Of the extra tax due.
Of the extra tax due.
Of the extra tax due — see HMRC's penalties for inaccuracies factsheet.
Disclosing an error to HMRC yourself, and cooperating fully with the check that follows, is what brings a penalty down toward the lower end of each range, and the quality of that disclosure genuinely changes the outcome.
Correspondence, deadlines and disclosures tracked together — so nothing is missed while a case is live.
How Far Back HMRC Can Go
HMRC's power to raise an assessment isn't unlimited, but it extends much further than most people expect. See HMRC's own table of assessing time limits for Income Tax and Capital Gains Tax.
The standard time limit for an ordinary case.
Where the loss of tax resulted from careless behaviour.
Where deliberate behaviour is involved — 12 years for offshore matters, extending to 20 if that offshore loss was also deliberate.
A single year under review can quickly become several once HMRC's questions widen, which is why an accurate first response matters far beyond the year actually being checked.
If You Disagree: Appeals and the Tax Tribunal
You don't have to accept an HMRC decision you believe is wrong.
Income Tax, Corporation Tax, CGT
You must first request an internal review from HMRC before appealing further.
VAT and other decisions
These can usually go straight to appeal at the independent First-tier Tribunal.
From there, the independent First-tier Tribunal hears both sides and can uphold, replace or send back HMRC's decision. We prepare and manage appeals at every stage, from the initial review through to Tribunal representation, so a disputed decision doesn't simply stand because no one challenged it.
What We Do For You
Whatever stage a compliance check or investigation has reached, we manage it end to end.
Initial response and case assessment
Reviewing HMRC's letter and your position before anything is sent back.
Full case management
Handling correspondence, requested information and deadlines throughout the check.
Code of Practice 8 and 9 representation
Including advice on the Contractual Disclosure Facility and preparing outline and formal disclosures.
Independent review of your position
Identifying where a penalty or assessment can reasonably be challenged.
Alternative Dispute Resolution
Where it offers a faster route than a formal appeal.
Appeals and Tribunal representation
Carrying a dispute through HMRC's internal review and, where necessary, to the First-tier Tribunal.
Why Businesses and Individuals Choose Finance Equation
We're an award-winning, ACCA-regulated practice with more than 30 years advising individuals and businesses across London through HMRC compliance checks, fraud investigations and disputes. We've managed cases through to completion with major regulatory bodies and auditors, and that experience is exactly what a serious HMRC matter needs — someone who has been through the process before, not learning it alongside you.
Because we're chartered certified accountants first, you get a specialist who understands both the tax technical position and how HMRC's investigators actually work — someone who deals with them directly on your behalf, so you're never left to explain yourself alone.