NT Tax Code: Why HMRC Is Taking Zero Tax From You
The NT tax code means no tax is deducted from your pay. That sounds ideal, but it could leave you facing a surprise bill. Here is what to do.
The three letters on your payslip that look like a gift from HMRC are actually a warning sign. If your tax code reads NT, you are paying no income tax whatsoever on that income source, and in most cases, that is not because you are entitled to it.
- NT stands for No Tax. It means your employer or pension provider deducts zero income tax from your payments.
- NT codes are legitimate in specific circumstances, but they are also frequently issued in error, leaving workers with an unexpected tax bill at year end.
- If you did not specifically request an NT code from HMRC or know why you have one, check your tax code now.
- HMRC can recover underpaid tax through future tax codes or a Self Assessment bill, sometimes years later.
- Workers with multiple income sources are especially vulnerable to NT code errors that go unnoticed for months.
- NT Tax Code
- NT stands for No Tax. When an employer or pension provider sees this code on a P45 or P6 instruction from HMRC, they deduct zero income tax from every payment, regardless of how much the worker earns. It is one of a small number of special tax codes that sit outside the usual alphanumeric system (like 1257L or 0T).
Zero Tax Deducted. That Is the Whole Story, Right?
Not quite. The NT code is legal. HMRC issues it deliberately in a narrow set of circumstances. The problem is that it is also issued in error more often than HMRC would like to admit, and because it results in more money arriving in your bank account each month, most employees do not question it. By the time anyone notices the mistake, months of underpaid tax have stacked up.
If you have spotted NT on your payslip and you are not certain why it is there, check your tax code now at /check-my-tax-code before reading another word. The answer matters more than the explanation.
For everyone who wants the full picture, here it is.
When the NT Tax Code Is Completely Legitimate
HMRC does issue NT codes intentionally. These are the situations where zero tax deduction is the correct outcome.
Non-UK Residents Working Temporarily in the UK
This is the most common legitimate use. Under double taxation treaties that the UK holds with dozens of countries, some workers who are tax resident elsewhere are not liable for UK income tax on their UK earnings. In those cases, HMRC instructs the employer to use NT so the employee is not taxed twice, once in the UK and once at home. The individual still declares the income in their home country and pays tax there.
Specific Pension Arrangements
Some pension annuities, particularly those paid to non-UK residents or under very specific trust arrangements, are issued with NT codes. Certain trivial commutation payments (small, one-off pension pot payouts below a threshold) can also be taxed separately rather than through PAYE, sometimes resulting in an NT code being applied temporarily.
Emergency Payroll Situations
Occasionally, a new employer cannot get a P45 from a previous employer or establish the correct code in time. Rather than default to the 0T tax code (which taxes every pound at the basic rate from the first penny), some payroll systems temporarily issue NT while the situation is resolved. This should be corrected within one or two pay periods.
Agency Workers and Complex Payroll Structures
Some contractors paid through umbrella companies or personal service companies have complex arrangements where tax is handled at a different stage of the payment chain. NT codes can appear in these setups, though they are frequently a source of compliance problems.
When the NT Tax Code Is a Serious Problem
If none of the legitimate scenarios above apply to you, NT on your payslip is almost certainly an error, and it is an error that will cost you money eventually.
Here is the mechanics of why. Your personal allowance for 2025/26 is £12,570. Above that, you pay 20% on income up to £50,270, then 40% on anything above. Under an NT code, your employer collects none of this. The money lands in your account, you spend it, and then at year end HMRC reconciles what was actually due.
Say you earn £38,000 and spend an entire tax year on an incorrect NT code. The tax due on that income (after your personal allowance of £12,570) is roughly £5,086. Every penny of that is still owed to HMRC. They will collect it either through a P800 tax calculation sent after the tax year ends, by adjusting your tax code in the following year to claw it back over twelve months, or by requiring you to complete a Self Assessment return.
Clawback through a future tax code is particularly punishing. HMRC will reduce your coding notice the following year by enough to recover the debt, which means your net pay drops noticeably for an entire year. If the underpayment is large, they may spread it across two years, but you will feel it either way.
The Multiple Jobs Problem
People with more than one income source are the most likely to end up on an NT code without realising why. When you start a second job, your new employer requests a tax code from HMRC. If the P45 from a previous employer arrives late or is processed incorrectly, or if HMRC's records do not yet reflect your primary employment, the secondary employer may be issued NT as a placeholder.
This creates a scenario where you are paying the right tax on your main job (via 1257L or similar) but paying zero on your secondary income. Since both streams of money arrive in the same bank account, the shortfall is invisible until HMRC runs its end-of-year reconciliation.
If you have recently started a second job or have income from two employers simultaneously, check your tax code at /check-my-tax-code for both employments. The HMRC Personal Tax Account lists every active tax code against every PAYE source. You are looking for NT against any of them.
For a broader view of how HMRC calculates your tax code, the mechanics behind the coding notice are worth understanding before you call anyone.
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How HMRC Recovers Underpaid Tax from NT Errors
Understanding the recovery mechanism matters because it affects your cash flow planning.
P800 reconciliation. After each tax year ends on 5 April, HMRC cross-references what your employer(s) reported paying you against what tax was actually collected. If there is a shortfall above a de minimis threshold (currently £50), HMRC sends a P800 letter. This is not a fine. It is a calculation of what you owe. You can usually pay it directly or ask for it to be collected through your next year's code.
Simple Assessment. For larger amounts, HMRC may issue a Simple Assessment bill rather than a P800. This functions similarly but has a formal payment deadline, typically 31 January following the end of the tax year. Missing this deadline attracts interest and penalties.
Adjusted coding notice. This is the most common route for smaller underpayments. HMRC reduces your personal allowance in the following tax year by the amount of the debt, effectively collecting the underpaid tax in monthly instalments through your payslip. This can make your net pay confusingly lower than expected, especially if you do not understand how tax codes translate into monthly deductions.
Self Assessment. If you also file a Self Assessment return (for self-employed income, rental income, or earnings above £100,000), any PAYE underpayment including NT errors will be factored into your SA calculation. The debt becomes part of your January and July payment schedule.
For anyone wondering whether a previous NT error has already triggered a letter they missed, HMRC's P800 process is worth reading in full.
What If You Actually Qualify for NT?
If you are a non-UK resident, you cannot simply tell your employer to apply NT. The employer needs a formal P6 instruction from HMRC specifying the NT code. You or your tax adviser would need to apply to HMRC's PAYE office, providing evidence of your residence status and the relevant double taxation treaty.
The same applies if you have a pension or trust arrangement that genuinely qualifies. NT does not get applied informally. If someone has told you that you qualify for NT without involving HMRC directly, treat that advice with scepticism. The liability stays with you, not with whoever gave you the tip.
NT Codes and Umbrella Companies: A Specific Risk
If you work through an umbrella company, particularly in construction, IT contracting, or locum healthcare, be aware that NT codes have been used as part of disguised remuneration schemes that HMRC considers non-compliant. These arrangements typically involve pay being split between a small PAYE element (taxed normally) and a larger loan or advance (issued under NT or with no deduction) that the promoter argues is not taxable income.
HMRC has robustly challenged these structures for over a decade under the Loan Charge legislation. Workers who participated, often without fully understanding the arrangement, have faced significant tax bills, interest, and penalties. If your NT code is connected to any scheme that describes your pay as a loan, advance, or trust payment, take independent tax advice immediately. This is not a situation to resolve through your employer's payroll team.
The Practical Steps If NT Appears on Your Payslip
Here is a straightforward sequence to follow.
Step one. Log in to your HMRC Personal Tax Account at gov.uk and check the tax code listed for your current employment. Alternatively, use TapTax's free tool at /check-my-tax-code to see what HMRC holds and whether it looks correct for your situation.
Step two. Look at your last two or three payslips. Under the income tax deduction column, is zero consistently shown? If so, how many months has this been running?
Step three. Estimate the potential underpayment. Multiply your monthly gross pay by the number of affected months. Apply the basic rate (20%) to the portion above your prorated personal allowance. That rough figure is what could be waiting for you as a future bill.
Step four. Contact HMRC on 0300 200 3300 or use the online messaging function in your Personal Tax Account. State clearly that you believe NT has been applied in error and ask them to issue the correct code. Keep a note of the date, time, and any reference number given.
Step five. Notify your employer's payroll department once HMRC confirms a new code has been issued. Payroll teams can only act on official P6 notices from HMRC; they cannot change your code based on your say-so alone.
For the broader process of disputing and correcting a wrong code, the exact steps to fix an incorrect tax code covers this in detail, and how long HMRC takes to fix a wrong tax code sets realistic expectations for the timeline.
The Reassurance You Actually Need
Discovering an NT code error is unsettling, but it is fixable. HMRC allows underpayments below £3,000 to be collected through the following year's code rather than as an immediate lump sum demand, provided you notify them before 31 December following the end of the tax year in question. This is set out in HMRC's own Extra-Statutory Concession A19, though ESC A19 also provides a separate route to have the debt waived entirely if HMRC's own error caused you to under-pay and you could not reasonably have known.
The key is not to ignore it. An NT code that sits unchallenged for two or three years compounds the problem considerably. HMRC can pursue underpaid income tax for up to four years under normal circumstances, and up to six years where it suspects careless behaviour.
You spotted the NT code. That is the hard part. Now check your tax code at /check-my-tax-code and let the process resolve what your payroll team should have caught months ago.
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