Tax investigation insurance pays the professional fees your accountant charges to handle an HMRC enquiry or compliance check. It does not pay the tax. If HMRC opens a check and finds you owe money, the tax, interest and any penalties are still yours to settle. What the policy removes is the bill for the defence.

That distinction is the whole product, and it is the thing most often misunderstood. Below is what actually happens in an HMRC check, why the fees mount, and where insurance does and does not help.

What the insurance covers

An HMRC check is correspondence. HMRC asks questions, your accountant answers them, HMRC asks more. Each round takes professional time, and that time is chargeable whether or not you have done anything wrong.

A policy responds to those professional costs: the accountant’s time in reviewing records, preparing responses, attending meetings, negotiating and, where it goes that far, taking the matter to tribunal. Cover typically extends across the taxes a business actually encounters, including income tax and corporation tax enquiries, PAYE and National Insurance reviews, VAT disputes, IR35 status challenges, Schedule 36 information notices, inheritance tax and stamp duty enquiries, and Companies House matters.

What it does not cover is the liability itself. No tax fee protection policy pays your tax, your interest or your penalties, and any that claimed to would be selling something quite different.

Why HMRC opens a check

HMRC’s own guidance is blunt about it: “Your tax affairs may be checked to make sure you’re paying the right amount.” Selection is largely risk-based, driven by data matching and anomaly detection, but a proportion of checks are genuinely random. Being selected is not an accusation.

That matters commercially, because the most common objection to this insurance is some version of “we have nothing to hide”. Having nothing to hide affects the outcome. It does not affect the cost of getting there.

The window is shorter than most people think, and longer

This is the part worth understanding properly, because it drives when cover matters.

The enquiry window. Where a return is filed on or before its deadline, HMRC has twelve months from the date the return is received to open an enquiry. Where a return is late, the window runs to the quarter day following the first anniversary of the date the return was made, the quarter days being 31 January, 30 April, 31 July and 31 October. Amend a return and HMRC gets a fresh window on the amendment.

So on a filed and unamended return, twelve months and the year is closed.

Except that a closed year can be reopened. Where HMRC discovers an under-assessment outside the enquiry window, it can raise a discovery assessment. The normal assessing time limit is four years from the end of the relevant tax period. Where the loss of tax was brought about carelessly, six years. For offshore matters, twelve. Where it was brought about deliberately, twenty.

Four, six, twelve, twenty. A business that believes its exposure ended twelve months after filing is working with a quarter of the real picture.

Making Tax Digital has changed the risk profile

Making Tax Digital for Income Tax went live on 6 April 2026 for sole traders and landlords with qualifying income above £50,000 for the 2024 to 2025 tax year. The threshold drops to £30,000 from 6 April 2027, and to £20,000 from 6 April 2028.

The relevance here is not the software. It is that quarterly updates replace a single annual filing event with several, each one a point at which something can be wrong, corrected, or queried, and each one generating a data trail HMRC can compare against the others and against third-party data.

More filing events and better data matching mean more anomalies surfaced. For accountants advising affected clients through the first full cycle, that is a live conversation to be having now rather than after the first wave of enquiries lands.

The kinds of check, and what each costs in time

An aspect enquiry looks at one item on a return. It can be resolved in a few letters, or it can widen.

A full enquiry examines the return as a whole and routinely runs for months. This is where fees become serious, because the work is not one answer but a sustained exchange.

A VAT or PAYE compliance visit involves HMRC attending, reviewing records and raising queries afterwards. HMRC confirms you may have an accountant or legal adviser present, and that presence has a cost.

An IR35 or employment status challenge turns on contractual analysis and working practices. These are argued, not simply answered, and the professional time reflects it.

A Schedule 36 information notice is a formal demand for documents or information under Finance Act 2008. Ignoring one without a reasonable excuse attracts penalties in its own right. Responding properly means someone reviewing what has been asked for, what must be provided, and what falls outside the notice.

The pattern across all of them is the same. The cost is not the answer. It is the number of times you have to answer.

Common misconceptions

Does it pay the tax I owe?

No. It covers professional fees for defending the check. Any tax, interest or penalties remain yours.

Can I buy it once HMRC has already contacted me?

No. Like any insurance, it covers events that arise after cover starts. A check that has already been opened is not an insurable risk, and no reputable insurer will write it. This is the single reason the product has to be bought before it is needed.

Do I have to change accountant?

Not with a policy that is written properly. Cover should respond to your own accountant’s fees. Arrangements that require you to use the insurer’s appointed representative are a materially different proposition and worth identifying before you buy.

Is being selected a sign HMRC suspects something?

Not necessarily. Selection is largely risk-based, and some checks are random.

Doesn’t HMRC pay my costs if I’m found to be right?

Generally not. A taxpayer who is entirely vindicated will usually still have paid their accountant for the work of getting there. Costs awards exist at tribunal but are the exception rather than the rule, and most checks never reach a tribunal.

Is the premium deductible?

Where the cover relates to the business, the premium is normally treated as a business expense. Treatment depends on the entity and the policy, so it is a question for your accountant rather than your broker.

Who it suits, and who it does not

The businesses that benefit most are those where an enquiry would be disruptive but not existential: owner-managed companies, partnerships, sole traders and landlords with enough complexity to attract questions and not enough spare cash to absorb a five-figure professional bill without noticing.

It suits less well where affairs are genuinely simple and static, or where the business is large enough to treat professional fees as a routine operating cost.

For accountancy practices, the calculation is different again. A practice scheme lets the firm offer cover across its client base, which protects the practice’s own fee recovery when a client faces a lengthy enquiry and cannot pay for the defence.

How it is bought

Two routes. Directly, as an individual policy for your own business, which you can quote for online. Or through your accountant, where the practice operates a scheme and cover is offered to clients as part of the annual engagement.

The questions worth asking whichever route you take: what is the limit, is there an excess, whose fees does it pay, does it cover enquiries into earlier years already filed, and what is specifically excluded. The last of those is where policies differ most and where the marketing tends to go quiet.

This guide is general information about how tax investigation insurance works and how HMRC compliance checks operate. It is not tax advice or a personal recommendation, and it does not describe the terms of any particular policy. Cover, limits and exclusions vary between policies, and you should read the policy documentation and speak to your accountant about your own circumstances.

Solar Protect is a trading style of Solar Insurance Services (Medway) Limited, which is authorised and regulated by the Financial Conduct Authority under firm reference number 459582.

Sources: HMRC guidance on tax compliance checks; HMRC Enquiry Manual EM1506 on enquiry time limits; HMRC Compliance Handbook CH52100 and CH53000 on assessing time limits; HMRC guidance on Making Tax Digital for Income Tax thresholds and dates.

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