Behind on Your Taxes or Can't Pay HMRC? What to Do Next

If you're reading this because a tax return is overdue, a letter is sitting unopened, or a bill has arrived that you can't pay, the most useful thing to know upfront is this: none of it is unusual, and none of it is unfixable. Professionals who work in this area deal with exactly this every week. This guide walks through why people end up here, what actually happens at each stage, and the established, non-dramatic routes for putting things right — whether that's catching up on filing, agreeing a payment plan, or disclosing income that was never declared. If you'd rather talk it through directly, register your enquiry and describe your situation in your own words — there's no need to have the terminology right first.

You're Not the First Person to Be Here

It's easy to feel like falling behind on tax is a uniquely embarrassing problem, but HMRC deals with unfiled returns, unpaid bills and unopened letters constantly, and the systems for dealing with all three are well-established, not punitive by default. The single biggest factor in how badly a situation like this turns out is usually how long it's left, not how it started.

Nothing in this guide requires you to have already worked out what's gone wrong or how much you owe. That's exactly the part a professional helps with — you don't need to arrive with answers, just a willingness to start.

Why This Happens

There's rarely one single cause, and none of the common ones are unusual.

• A first return was missed by a small margin, and each year after felt harder to address than the last.
• A life event — illness, bereavement, separation, a business closing — meant tax simply wasn't the priority at the time.
• Income from a side project, rental property or overseas source was never quite declared, without a clear decision ever being made not to.
• A letter arrived that looked complicated or threatening, and it felt easier not to open it than to face what was inside.
• A previous bill went unpaid because the money genuinely wasn't there at the time, and it's grown since through interest and penalties.

If more than one of these sounds familiar, that's normal too — these things tend to compound rather than happen in isolation.

If You're Behind on Filing

Whether it's one missed return or several years, the approach is broadly the same: work out what's actually owed, file the returns, and deal with any penalties afterwards, generally in that order.

• You can usually still register and file even years after a deadline has passed — the door doesn't close, though penalties and interest will typically apply the longer it's left.
• If a return still hasn't been filed, HMRC can issue an estimated tax bill based on limited information, which is often higher than the real figure — filing the actual return usually replaces this with a more accurate one.
• Gathering records gets harder the further back you go, but a professional can often reconstruct a reasonable picture even from incomplete information — bank statements alone can go a long way.
• Multiple outstanding years are usually filed oldest first, since later years sometimes depend on figures carried forward from earlier ones.
• Filing itself doesn't require the money to pay whatever's owed to be ready yet — those are two separate steps, and getting the return in is the priority.

If You Owe Money and Can't Pay It

Owing more than you can pay in one go is common, and HMRC has a formal, named route for exactly this situation.

• HMRC's Time to Pay arrangement lets you spread a tax debt over instalments rather than paying it in a single amount, and smaller Self Assessment debts can often be set up for this online without needing to speak to anyone.
• Larger or more complex debts, or a Time to Pay arrangement that's already been broken before, usually need a conversation with HMRC directly, which a professional can help prepare for or handle on your behalf.
• Contacting HMRC before a payment is missed, rather than after, is generally treated more favourably and opens up more options than waiting for a chasing letter to arrive first.
• Interest continues to accrue on the outstanding balance during a payment plan, so it's still worth paying it off faster if your circumstances improve, rather than treating the agreed schedule as fixed.
• None of this affects only the anxious-sounding cases — plenty of Time to Pay arrangements are agreed for straightforward reasons like a slow-paying client or an unexpected bill elsewhere.

If There's Income You've Never Declared

Rental income, a side business, overseas income or savings interest that's never made it onto a return is one of the more common things people quietly worry about. HMRC has established, named disclosure routes built specifically for this.

The consistent theme across all of these is that coming forward voluntarily, before HMRC contacts you about it independently, is treated significantly more favourably than being found first — often meaning lower penalties than the same disclosure made reactively. A professional can handle the disclosure process directly, which matters here more than almost anywhere else in this guide, since these submissions have a specific format HMRC expects.

Letters, Penalties and What They Actually Mean

Not every HMRC letter means the same thing, and opening it is almost always less bad than what's been imagined.

• A reminder or nudge letter is usually just that — a prompt, not an escalation, and often the easiest point to act at.
• A penalty notice confirms a specific amount for a specific reason (late filing, late payment) and will explain what it's for and how to appeal if you disagree or have a reasonable excuse.
• A "compliance check" or enquiry letter means HMRC wants more information about a specific return, which doesn't automatically mean something is wrong — but is worth responding to properly, ideally with help.
• "Reasonable excuse" is a real, recognised concept for appealing a penalty — genuine reasons like serious illness or bereavement around the deadline are often accepted, though what qualifies varies by situation.
• Ignoring any of these doesn't make them go away — it typically leads to a firmer follow-up letter, not a quieter one.

If you're holding an unopened letter right now, opening it and finding out what it actually says is almost always the single most useful thing you can do today, even before contacting anyone else about it.

What a Professional Actually Does in This Situation

Beyond the technical filing and disclosure work, a professional's role here is largely about taking the situation off your hands and dealing with HMRC directly on your behalf.

• Working out what's actually owed, which is often less frightening than the uncertainty of not knowing.
• Filing outstanding returns in the right order, using whatever records are actually available.
• Contacting HMRC directly — including negotiating a Time to Pay arrangement or handling a voluntary disclosure — so you're not doing it alone.
• Appealing a penalty where a reasonable excuse genuinely applies, rather than assuming it's not worth trying.
• Setting up whatever's needed so the same situation doesn't recur next year, once the immediate issue is sorted.

What Tends to Make Things Worse

• Leaving a letter unopened, which delays finding out it's often simpler than expected.
• Waiting to have all the answers before getting in touch with anyone, rather than starting with what you do know.
• Assuming a missed year makes future years pointless to file properly, when each year is still assessed on its own basis.
• Avoiding HMRC entirely rather than contacting them before a deadline is missed, which closes off options that were otherwise available.
• Believing the situation is somehow uniquely bad, which mainly just delays reaching out for help.

Getting Help, Starting Today

None of the routes in this guide require you to have this fully worked out before you ask for help — quite the opposite. A professional who deals with catch-up filing, payment plans and voluntary disclosures regularly can tell you within one conversation roughly what you're dealing with and what the realistic next step looks like.

Wherever you're based, tell us your postcode or town when you register an enquiry — see our full list of locations for more. Whatever your situation, describing it honestly in your own words is enough to get started.

Frequently Asked Questions

A few more common questions from people in this situation — see our full FAQ page for more, or get in touch directly if yours isn't covered here.