What happens if I register for self-assessment but don’t submit a return?

What happens if I register for self-assessment but don’t submit a return?

Registering for Self Assessment can feel like you’ve done the hard part: you’ve told HMRC you need to deal with tax in a more formal way, you’ve got a Unique Taxpayer Reference (UTR), maybe you’ve even set up an online account. Then life gets busy, the deadline creeps up, and you start wondering: “What if I just… don’t submit the return?”

If you’re in the UK, the short version is that registering for Self Assessment creates expectations. HMRC generally assumes you will submit a tax return when you are issued a notice to file. Failing to do so can lead to automatic penalties, interest on late-paid tax, possible enforcement action, and stress you probably don’t need. The exact consequences depend on whether HMRC has actually asked you to file, whether you owe tax, and what you do next.

This article walks through what usually happens after you register, what triggers penalties, how HMRC calculates late filing penalties, what the late payment consequences can look like, and the practical steps to reduce damage if you’ve missed a deadline or you think you shouldn’t have been in Self Assessment in the first place.

Registering vs. being required to file: the key distinction

It’s easy to assume that “registering for Self Assessment” automatically means “I must file a return every year forever.” In practice, there are two related but separate ideas:

1) Being registered (having a UTR and Self Assessment record). This means HMRC can administer your tax through Self Assessment if needed.

2) Being required to submit a return for a particular tax year. This generally happens when HMRC issues you a “notice to file” (sometimes called a notice to deliver a return). That notice is what makes a tax return legally due for that year.

So what happens if you register but don’t submit? The most common scenario is: you register, HMRC expects to receive a return, and they either issue a notice to file (often automatically) or already have a reason to think you need to submit for that year. Once a notice to file exists, missing the deadline usually triggers penalties even if you end up owing no tax.

There’s also another scenario: you registered, but HMRC did not issue a notice to file for that year (or you successfully got it withdrawn). In that case, you may not be legally obliged to submit a return for that year. However, it’s not safe to assume this without checking your online account or contacting HMRC, because in many cases a notice is issued and you might not realise until penalties appear.

Why HMRC might expect a return after you register

People register for Self Assessment for lots of reasons: self-employment, rental income, dividend income, capital gains, foreign income, child benefit charge, or because their PAYE doesn’t cover everything. Often, you register because you genuinely need to. Other times, you register “just in case,” or because a bank, landlord, client, or friend told you it was the right thing, or you had a one-off situation that won’t repeat.

HMRC’s systems tend to treat registration as a signal that a return will be needed. That doesn’t mean you’ll be forced to file every year forever, but it does mean you should be proactive: either file the return, or confirm you don’t need to and get the notice to file withdrawn (if appropriate).

Many of the penalties that frustrate people arise from this mismatch: someone registers, later discovers they didn’t actually need to file for a year, but HMRC still issued a notice to file. If the notice is left in place and the deadline passes, the computer-generated penalties can start stacking up.

What triggers penalties: the notice to file and the deadlines

Late filing penalties usually start when two things are true:

• HMRC issued a notice to file for that tax year.

• You miss the submission deadline.

In the UK, the tax year runs from 6 April to 5 April. Deadlines depend on whether you file on paper or online. Online filing has a later deadline than paper filing. People who register late or who are new to Self Assessment sometimes get caught out by which method applies and what their account is set up for.

Even if you owe no tax, late filing penalties can still be charged simply because the return wasn’t submitted by the deadline. That’s one of the most important points to understand: the return obligation and the payment obligation are related but separate. Filing late can cost you even when payment would have been £0.

The typical late filing penalty timeline

Although exact amounts and rules can depend on the year and your situation, Self Assessment late filing penalties often follow a predictable timeline. The initial penalty for missing the deadline is typically a fixed amount. After that, additional penalties can be charged if the return remains outstanding for longer periods.

Here’s how it commonly escalates:

1 day late: A fixed late filing penalty is charged as soon as the deadline is missed.

3 months late: Daily penalties can start accruing for a period, which can push the total up quickly.

6 months late: Additional penalties can apply, often based on a percentage of tax due or a minimum amount.

12 months late: Further penalties can apply, potentially higher if HMRC considers the delay deliberate or if information is withheld.

What matters for you is not memorising the numbers but understanding the principle: once late filing penalties start, they can compound. The longer you leave it, the more expensive and stressful it becomes to unwind.

Late payment vs. late filing: two sets of consequences

People often fixate on filing because it’s the visible admin task. But HMRC also cares about paying tax on time. If you owe tax and don’t pay by the deadline, you can be charged late payment penalties and interest.

Late filing penalties are about the return being missing.

Late payment penalties and interest are about tax being unpaid after it’s due.

You can be hit by both at the same time. For example, if you file late and also pay late, penalties and interest can run in parallel. Alternatively, you might file late but owe nothing—then you might “only” face late filing penalties. Or you might pay an estimated amount on time but forget to file—then you could still face late filing penalties even though you paid.

Interest is especially frustrating because it keeps ticking until the tax is paid. Penalties are often staged at specific milestones. Together, they can create a bill that feels disproportionate to the original tax due—especially if the amount of tax was small.

What if you don’t owe any tax?

This is where many people feel the system is unfair: “How can I be fined when I don’t owe anything?” The answer is that the obligation is to submit the return when you’ve been asked to do so. HMRC uses returns not only to collect tax but also to confirm your position, ensure records are accurate, and maintain compliance across the system.

If you submit late and your liability is nil, you may still have penalties for the late return. However, in some situations, if you genuinely didn’t need to be in Self Assessment for that year, there may be options to have the notice to file withdrawn and, with it, the penalties cancelled. This is not automatic, and it typically requires action from you.

The practical takeaway: don’t ignore the problem just because you think you don’t owe tax. If HMRC expects a return and you don’t file, the penalties can still pile up.

What if you do owe tax?

If you owe tax and don’t file, the consequences can be more severe and more expensive. HMRC may not know your true liability without a return. If you’ve had self-employment profits, rental income, capital gains, or other taxable income outside PAYE, HMRC could treat the missing return as a serious compliance issue.

When a return is overdue, HMRC can issue assessments based on estimates. These are sometimes called “determinations” in certain contexts. The estimate might be higher than your actual liability, because HMRC would rather protect the tax position than undercharge. The burden often shifts to you to submit the return to replace the estimate with the correct figures.

In addition, if HMRC believes the failure to file is deliberate or that you’re concealing income, they can open enquiries and, in more serious cases, pursue civil penalties at higher levels and potentially criminal investigation. Most people are not in that territory—many are simply overwhelmed or confused—but it’s important to recognise that ignoring a tax return can move your situation from “admin mistake” into “non-compliance” in HMRC’s eyes.

How HMRC contacts you (and why you might miss it)

Part of the danger is that you might not notice the triggers until it’s too late. HMRC might contact you through:

• Messages in your online tax account

• Letters sent to your last known address

• Emails prompting you to log in (often without details, for security)

• Text reminders (if you’ve opted in)

If you’ve moved house and didn’t update your address, or you don’t regularly check your online account messages, you can miss a notice to file or reminders. Unfortunately, “I didn’t see the letter” is rarely a winning argument by itself, especially if the issue is an address you failed to update. That said, there are situations where communication failures do happen, and you may be able to challenge penalties if you can show you had a reasonable excuse and acted promptly once you became aware.

What happens after the deadline: the usual progression

If you don’t submit a return after registering (and a notice to file exists), a common progression looks like this:

Step 1: Automatic late filing penalty appears. This can show in your online account as an amount due.

Step 2: Reminder letters and prompts escalate. HMRC might send further reminders or warnings.

Step 3: Additional penalties accrue. The longer the return is outstanding, the more penalties can be added.

Step 4: HMRC estimates your tax or takes enforcement steps. If there’s tax potentially due, HMRC may issue assessments or pursue collection activity.

Step 5: Debt collection and enforcement options. For unpaid amounts, HMRC can use various collection methods. These can include debt collection agencies, collecting through PAYE (in some cases), or stronger enforcement tools in more serious situations.

This progression is not a script that plays out identically for everyone. It depends on whether HMRC believes tax is due, the amounts involved, your past compliance history, and whether you respond. But the central point is: doing nothing tends to make the situation worse, not better.

Can HMRC remove you from Self Assessment if you don’t need it?

Yes, in many cases you can ask to be removed from Self Assessment going forward if you no longer meet the criteria to submit returns. For example, you might have stopped being self-employed, your rental income stopped, or you had a one-off reason to register that no longer applies.

However, being removed going forward does not automatically clean up an outstanding return for a past year. If a return is already due for a year and the notice to file remains in place, you may still need to submit it or get that notice withdrawn.

In other words: “closing” Self Assessment is not always the same as “cancelling” an overdue return. You may need to deal with both parts: stop future returns if appropriate and resolve past obligations and penalties.

What if you registered by mistake?

It happens more often than you’d think. People register because they think they must, because they earned money on the side, because they started self-employment but never actually traded, or because they confused registration for something else entirely.

If you genuinely did not need to submit a return for a particular year, you may be able to ask HMRC to withdraw the notice to file. If HMRC agrees, penalties linked to that notice can often be cancelled because, in effect, the legal requirement to file for that year is removed. The important part is timing and evidence. HMRC will generally want to understand why you registered, what income you had, and whether PAYE already dealt with it.

Be careful: “I didn’t know” is not the same as “I didn’t need to.” If you had taxable self-employment profits, rental income, capital gains, or other income not taxed at source, you likely did need to file even if you weren’t aware of it.

Reasonable excuse: when penalties can be appealed

If you were required to file and missed the deadline, you might still be able to appeal penalties if you had a reasonable excuse. A “reasonable excuse” is not a magic phrase; it’s a factual explanation of why you couldn’t meet the obligation despite taking reasonable care, and why you acted as soon as you could.

Examples that can sometimes support an appeal include serious illness, bereavement close to the deadline, unexpected hospitalisation, IT failures at critical times (with evidence), or events like fires or floods that destroyed records. Being busy, forgetting, or not understanding the rules typically does not succeed on its own, though each case turns on its facts and how you present them.

Even when you have a strong reason, the way you act afterwards matters. If you had a genuine disruption but then waited many months before doing anything, HMRC may argue that the reasonable excuse ended and you still didn’t take action promptly.

What if you can’t access your online account?

A very practical problem: sometimes people don’t file because they can’t log in, lost access to their authentication method, never received their activation code, or are locked out. If that’s you, don’t let it become the reason you do nothing. You can take steps such as resetting access, requesting new codes, or contacting HMRC for help. If you’re close to a deadline, it can also be better to act fast and document what’s happening rather than waiting and hoping the issue resolves itself.

When technical or access issues are genuinely preventing filing, keep records: dates, screenshots, error messages, reference numbers for calls, and notes of what you were told. Evidence makes a big difference if you later need to appeal penalties.

How long can you leave it before it becomes a bigger problem?

If you’ve missed the deadline, you might feel tempted to ignore it because you’re anxious or embarrassed. Unfortunately, the system is designed to punish delay. The later you file, the more penalties can accrue, and the more likely HMRC is to take stronger action—especially if they suspect tax is due.

In practical terms, there are three time-related risks:

• Escalating penalties: The longer a return is outstanding, the higher the late filing penalties can go.

• Accruing interest and late payment penalties: If tax is due and unpaid, interest can accumulate and payment penalties may be added.

• Administrative complexity: The longer you wait, the harder it can be to reconstruct records and the more stressful it is to deal with letters, calls, and potential assessments.

If you’re already late, filing sooner rather than later usually reduces the total cost and risk, even if you can’t pay immediately. Submitting the return stops late filing penalties from continuing to grow, and it clarifies what you actually owe.

Should you file even if you can’t pay right now?

Often, yes. Filing and paying are separate obligations. Submitting the return on its own can prevent further late filing penalties and can put you in a better position to negotiate a payment plan if you owe tax.

HMRC may be more willing to agree to a time-to-pay arrangement when your affairs are up to date and the liability is clear. If you haven’t filed, it’s harder for anyone—including you—to know what the true amount is and how to plan for it.

That said, don’t guess wildly. If you don’t have the figures, you may need to gather records or get help from an accountant. But as a general rule, “I can’t pay” is not a good reason to avoid filing.

What if you submitted nothing because you had no income?

Another common scenario is: you registered as self-employed, but then you didn’t actually trade, or you earned below thresholds, or you had a year with no taxable income. You might think that means “no return needed.” Sometimes it does, sometimes it doesn’t.

If HMRC issued you a notice to file, you usually still need to submit a return (even a “nil” return) unless the notice is withdrawn. A nil return is essentially you telling HMRC, formally, “There’s nothing to tax this year.” It can feel pointless, but it closes the loop and prevents penalties from continuing.

If you truly had no reason to be within Self Assessment for that year, you might be able to ask HMRC to withdraw the notice instead. The right approach depends on your facts and how quickly you can resolve it.

How to check whether you actually have a return due

If you’re unsure whether HMRC expects a return, you should check rather than guess. Practical ways to do that include:

• Logging into your HMRC online account and looking at your Self Assessment status, messages, and what tax years are listed as “due” or “overdue.”

• Reviewing any letters you’ve received that mention a notice to file or a requirement to submit a return for a specific year.

• Calling HMRC (or using other official contact methods) and asking explicitly: “Do I have a notice to file for tax year X to Y?” and “Can it be withdrawn if I don’t need to file?”

The most important detail is the specific tax year. People sometimes get confused and think they’re late for a year that isn’t due, or they miss that it’s a different year than they assumed.

Practical damage control: what to do if you didn’t submit

If you registered for Self Assessment but didn’t submit a return, here is a practical approach that often works well:

1) Confirm which tax year(s) are outstanding. Don’t guess. Check your account or confirm with HMRC.

2) Decide whether you should be filing or asking to withdraw the notice. If you had taxable income that requires a return, plan to file. If you genuinely didn’t need a return, pursue withdrawal of the notice.

3) Submit the return as soon as possible if it’s due. Even if you’re late, getting it done stops the “return outstanding” problem from continuing.

4) Calculate what you owe and prioritise payment. If you can’t pay in full, explore payment arrangements. Don’t ignore the bill.

5) Appeal penalties if you have grounds. If you had a reasonable excuse or the notice should not have been issued, appeal. Provide clear facts and evidence.

6) Consider professional help if the situation has escalated. If multiple years are outstanding, penalties have grown, or HMRC has issued estimates you disagree with, an accountant or tax adviser can help you correct the record and communicate effectively.

Common misconceptions that lead to trouble

Let’s tackle a few beliefs that often cause people to delay:

“If I ignore it, it will go away.” Usually the opposite. Penalties can accrue and enforcement can escalate.

“I didn’t earn much, so they won’t care.” HMRC’s systems are driven by process. If a return is due, the system can issue penalties regardless of amounts.

“I’ll just file next year instead.” Returns are annual and year-specific. Skipping one year doesn’t get fixed by filing another.

“I can’t file because I’m not sure of the numbers.” Uncertainty is common, but you can often reconstruct records, use bank statements, request duplicate invoices, or seek help. Waiting tends to make it harder, not easier.

“I registered so HMRC will calculate it for me.” Under Self Assessment, the responsibility is generally on you to report income and calculate liability, even though HMRC provides tools and guidance.

How long do you need to keep dealing with Self Assessment?

Many people assume that once they’re in Self Assessment, they are trapped. Not necessarily. If the reason you registered no longer applies, you can often ask HMRC to stop sending returns for future years. For example, if you return to employment with everything taxed under PAYE and you no longer have other reportable income, Self Assessment may not be needed.

But you should be careful about timing. If you’ve ceased self-employment or stopped rental income, you still may need to submit a final return to cover the period up to cessation, and you may need to formally notify HMRC. If you stop trading, you might also need to close down related registrations (like Class 2 National Insurance obligations, depending on your circumstances).

Think of it like closing a tab: you need to close it properly so it doesn’t keep running in the background.

What if HMRC has already charged penalties?

If penalties are already on your account, the situation is not hopeless. You typically have a few routes depending on why the penalties exist:

• File the outstanding return(s): This is often the first step regardless of what you do next, because it stops further late filing issues and replaces estimates.

• Appeal penalties: If you have a reasonable excuse, or if HMRC should not have required a return, you can appeal. Appeals often have time limits, but even if you’re outside those, you can sometimes ask HMRC to accept a late appeal if there’s a good reason.

• Request withdrawal of the notice to file (where appropriate): If HMRC agrees you didn’t need to file, penalties associated with that requirement can potentially be removed.

• Arrange payment: If penalties remain payable, set up a plan rather than ignoring them. Taking control reduces the risk of enforcement.

When you communicate with HMRC, clarity helps. Focus on the facts: the tax year, what income you had (or didn’t), when you registered, why you didn’t file, and what you’ve done to resolve it.

How to reduce stress and avoid repeating the problem

Once you’ve dealt with the immediate issue, it’s worth setting up a system so you don’t end up in the same place next year. Some practical habits:

• Put key dates in your calendar with reminders weeks in advance.

• Keep basic bookkeeping throughout the year rather than scrambling at the end.

• Keep a folder (digital or paper) for invoices, receipts, bank statements, and tax letters.

• Check your HMRC online account periodically for messages and status updates.

• If you stop needing Self Assessment, ask HMRC to confirm your status so you’re not issued returns unnecessarily.

If you’re self-employed or have ongoing income outside PAYE, consider using software or spreadsheets to track income and expenses. The goal isn’t perfection; it’s making it easy to file accurately and on time.

When it’s time to get help

Sometimes the best step is to involve a professional. Consider getting help if:

• You have multiple years of outstanding returns.

• HMRC has issued estimates that seem wrong.

• You have complex income (foreign income, capital gains, multiple properties, partnerships).

• Penalties are large and you believe you have grounds to appeal.

• You’re anxious and avoiding it—because avoidance itself can be costly.

A good accountant or tax adviser can help you file correctly, negotiate with HMRC, and present an appeal clearly. Even a one-off consultation can save money if it prevents unnecessary penalties or helps you withdraw a return you didn’t actually need to file.

Bottom line

If you register for Self Assessment but don’t submit a return, what happens depends on whether HMRC has issued you a requirement to file for that tax year. In many cases, failing to submit after a notice to file triggers automatic late filing penalties, which can escalate the longer the return remains outstanding. If you owe tax, you can also face late payment penalties and interest, and HMRC may estimate your tax and pursue collection.

The most effective response is usually to act quickly: confirm what’s due, file any outstanding return(s) if required, pay what you can, and explore payment arrangements if needed. If you truly didn’t need to file, seek withdrawal of the notice and challenge penalties where appropriate. The sooner you engage, the more control you’ll have over cost, stress, and outcomes.