1257L W1 Tax Code Explained: What It Means for Your Pay?

1257L W1 tax code means an employee is receiving the standard £12,570 Personal Allowance, but their Income Tax is being calculated on a Week 1 basis rather than cumulatively across the tax year.

In practical terms, payroll looks only at the employee’s pay for the current week. It does not take account of earlier earnings, tax already paid or unused Personal Allowance from previous weeks.

1257L W1 is therefore commonly described as an emergency tax code or non-cumulative tax code.

It often appears temporarily when someone starts a new job, changes employers or when HMRC does not yet have enough information to calculate their normal cumulative PAYE position.

What Does the 1257L W1 Tax Code Mean?

The code can be broken into three parts:

For the 2026/27 tax year, the standard Personal Allowance remains £12,570.

However, the important part of 1257L W1 is W1.

A normal 1257L code is generally operated cumulatively. That means payroll considers income and tax from the beginning of the tax year.

Under 1257L W1, each week effectively stands on its own.

Someone wanting more detail about the Week 1 marker can read about how the W1 tax code works and why it can produce different deductions from an ordinary cumulative code.

Is 1257L W1 an Emergency Tax Code?

Yes. 1257L W1 is one of the emergency PAYE tax codes used in 2026/27.

The standard emergency codes include:

• 1257L W1
• 1257L M1
• 1257L X

This does not mean the employee has done anything wrong or that HMRC believes tax is overdue.

“Emergency” mainly describes the way PAYE is being calculated while complete information is unavailable or while a temporary tax treatment is required.

It can be perfectly normal to see the code briefly after changing employment.

How Does 1257L W1 Work?

Under an ordinary cumulative 1257L code, payroll considers how much Personal Allowance should have accumulated from the beginning of the tax year.

It can therefore take account of:

• Previous taxable earnings
• Tax already deducted
• Unused Personal Allowance from earlier periods
• The employee’s PAYE position so far in the tax year

1257L W1 does not perform that cumulative calculation.

Instead, the employee receives approximately one week’s share of the standard Personal Allowance for that week’s pay.

For 2026/27, the standard PAYE Personal Allowance is approximately £242 per week.

If an employee earns £600 during a week, a simplified illustration would be:

This is only a simplified illustration. Actual PAYE deductions can vary depending on the employee’s earnings, tax band, taxable benefits and other adjustments.

What Is the Difference Between 1257L and 1257L W1?

Although both codes contain 1257L, they do not necessarily produce the same deduction.

The major difference is therefore not the amount of Personal Allowance represented by 1257L. It is the way that allowance and tax are calculated.

A fuller explanation of the underlying PAYE method can be found in the article on non-cumulative tax codes.

Why Have I Been Put on Tax Code 1257L W1?

There are several reasons 1257L W1 can appear on a payslip.

Starting a New Job Without a P45

One of the most common situations is starting employment when the new employer does not yet have complete information from the previous job.

Without accurate previous earnings and tax information, payroll may be unable to operate a cumulative tax code safely.

A temporary Week 1 code can therefore be used.

HMRC Has Not Yet Updated the Employer

There can be a short period between HMRC updating an individual’s tax position and the employer receiving or processing the new PAYE code.

During this period, an emergency code may remain on the payslip.

Returning to Work

Someone returning to employment after unemployment, self-employment, studying or another break may temporarily receive a Week 1 code while their current PAYE position is established.

Starting to Receive a Pension

Emergency codes can also appear when someone begins receiving pension income, particularly where the pension provider does not initially have complete tax information.

Employment Records Do Not Match

If HMRC records show more than one employment or an old job incorrectly remains active, the allocation of the Personal Allowance may need to be reviewed.

This can result in temporary tax-code changes.

Can 1257L W1 Make You Pay Too Much Tax?

It can.

The problem usually arises because unused Personal Allowance from earlier weeks cannot be carried forward under Week 1 treatment.

Consider someone who did not work during the first several weeks of the tax year and then started a new job.

Under a cumulative 1257L code, unused allowance from those earlier weeks could potentially be taken into account when calculating PAYE.

Under 1257L W1, payroll only considers the current week’s allowance.

The employee could therefore pay Income Tax immediately even though their overall income for the tax year suggests less tax should have been due at that point.

This does not necessarily mean the final tax bill will be wrong. The position can often be corrected when the correct cumulative code is subsequently applied.

Can 1257L W1 Make You Pay Too Little Tax?

Yes, that is also possible.

Because the code ignores earlier earnings and tax, it may not reflect the employee’s full tax-year position.

For example, someone who has already received substantial income elsewhere could temporarily have too little tax collected if the information available to payroll is incomplete.

That is why the code should not simply be judged by whether take-home pay has increased or decreased.

The important question is whether HMRC has the correct information about all relevant PAYE income.

What Happens to Unused Personal Allowance on W1?

Unused allowance from previous weeks is not carried forward when 1257L W1 is used.

This is one of the most important features of the code.

Suppose someone starts work several weeks into the tax year after having no taxable income.

A cumulative code could take account of the unused Personal Allowance accumulated before they started working.

A Week 1 code cannot.

Every payday is treated separately until the non-cumulative restriction is removed.

Is 1257L W1 the Same as 1257L M1?

The principle is the same, but the pay period is different.

1257L W1 is normally associated with weekly payroll.

1257L M1 is normally associated with monthly payroll.

With M1, each month is calculated independently rather than looking at total pay and tax since the start of the tax year.

Anyone paid monthly is therefore more likely to see 1257L M1 rather than W1. The 1257L M1 tax code follows the same basic non-cumulative principle.

Is 1257L W1 the Right Tax Code?

1257L W1 can be correct temporarily, especially after a change in employment.

However, an employee should investigate if:

• It remains on several payslips after starting a job
• Their previous employment information has already been provided
• Their pay has unexpectedly fallen
• They believe too much Income Tax is being deducted
• HMRC still shows an old employment
• Their employer has received a different tax code
• Their circumstances do not justify the standard Personal Allowance

Someone unsure about the underlying code can also check the factors used to determine whether a tax code is correct.

How Can You Get Off the 1257L W1 Tax Code?

The correct action depends on why the emergency code was applied.

Check Your Payslip

First, confirm exactly how the code appears.

Look for:

1257L W1

It may alternatively appear as:

1257L W1/M1, 1257L X, 1257L NONCUM or another payroll-system variation indicating non-cumulative treatment.

Check Your Employment Details

Make sure previous employment has been properly closed and the new employer has the necessary starter information.

Incorrect or duplicated employment records can affect how the Personal Allowance is allocated.

Give Payroll the Correct Information

If the employer is missing a P45 or another piece of starter information, supplying it may help resolve the issue.

However, employers cannot simply invent or choose whichever tax code an employee requests. Payroll normally has to operate the code HMRC instructs it to use.

Check Your Current Tax Code

The employee should check whether the tax code HMRC holds matches the code appearing on the payslip.

If HMRC already shows a different code, it may simply be waiting to reach or be processed by payroll.

Correct Inaccurate Information

If earnings, employment or pension information is wrong, it should be corrected so HMRC can recalculate the PAYE code.

Once HMRC issues a replacement code, the employer should normally use it in payroll.

Will I Get an Automatic Refund After 1257L W1?

A refund may be generated automatically if the code is changed from Week 1 treatment to an appropriate cumulative code during the same tax year.

When payroll applies the cumulative code, it can recalculate the employee’s position using total taxable pay and tax deducted so far.

If that calculation shows too much Income Tax has been paid, the adjustment may appear through a later payslip.

However, this depends on the circumstances. Not every person moving away from W1 is automatically owed a refund.

If the position is not corrected through payroll, the overall Income Tax position may need to be reconciled separately.

Does 1257L W1 Affect National Insurance?

No. A PAYE tax code determines how Income Tax is deducted.

It does not itself set the amount deducted for:

• National Insurance
• Workplace pension contributions
• Student loan repayments
• Postgraduate loan repayments

Those deductions operate under their own rules.

A payslip can therefore show the correct National Insurance deduction even when the Income Tax code needs to be reviewed.

What About Scottish and Welsh Taxpayers?

Taxpayers in Scotland and Wales normally have prefixes showing which Income Tax system applies.

A Scottish taxpayer may see a code beginning with S, while a Welsh taxpayer may see a code beginning with C.

The absence or presence of these prefixes matters because Scotland has different Income Tax bands and rates, while Welsh taxpayers are identified separately under PAYE.

Someone who has moved between parts of the UK should therefore make sure their address and taxpayer status are up to date.

Should You Worry About 1257L W1?

Seeing 1257L W1 on one of the first payslips from a new job is not automatically a cause for concern.

It often reflects a temporary lack of complete PAYE information.

It becomes more important to investigate when the code continues despite HMRC and the employer having accurate information, or when deductions appear inconsistent with the employee’s circumstances.

The key distinction is simple:

1257L gives the standard Personal Allowance, while W1 prevents payroll from calculating tax cumulatively.

Once the correct cumulative tax code is issued, PAYE can usually take account of the employee’s wider tax-year position.

Frequently Asked Questions

What does 1257L W1 mean on my payslip?

1257L W1 means the standard £12,570 Personal Allowance is being used, but PAYE is calculated only on the current week’s pay. Previous earnings, tax deductions and unused allowance are ignored for that calculation.

Is 1257L W1 a bad tax code?

Not necessarily. It is an emergency or non-cumulative code and can be appropriate temporarily, particularly after starting a new job.

Is 1257L W1 the normal tax code?

1257L itself is a common standard tax code. The W1 marker changes how it operates and makes it non-cumulative.

How long should I be on 1257L W1?

There is no single fixed period. It can remain until HMRC and payroll have enough information to operate the appropriate tax code. If it continues despite all employment information being correct, the employee should investigate.

Does 1257L W1 give me the £12,570 Personal Allowance?

The 1257L element represents the standard £12,570 Personal Allowance. However, W1 means only the relevant week’s portion is considered when calculating that week’s PAYE.

Will 1257L W1 cause emergency tax?

1257L W1 is itself an emergency tax code. It can result in more tax being deducted than under a cumulative code, particularly where the employee has unused Personal Allowance from earlier in the tax year.

Will I get emergency tax back?

If too much Income Tax has been deducted, it may be corrected through payroll after an appropriate cumulative code is applied. Whether a refund is due depends on the employee’s total income and tax position.

Can my employer remove W1 from my tax code?

An employer generally has to operate the tax code and basis supplied through the PAYE rules and HMRC instructions. Payroll should not simply remove W1 because an employee asks for it to be changed.

What is the difference between W1 and M1?

W1 calculates PAYE independently for each week. M1 calculates it independently for each month. Both are forms of non-cumulative emergency tax treatment.