UK Second Job Tax Calculator
See whether the default BR tax code on your second job over-withholds, under-withholds, or gets it right.
Is Your Second Job Taxed Correctly?
Actual Combined Tax Owed
£4,486
Default PAYE Withholding (Job 1 + BR Job 2)
£4,486
What Is the UK Second Job Tax Calculator?
When you take on a second PAYE job, HMRC typically assigns it the BR tax code by default — a flat 20% on everything from that job, with no Personal Allowance applied, since your main job is assumed to already be using it. This default assumption is often close enough, but not always: depending on how your income actually splits between the two jobs, it can either leave you paying too much, or — less obviously — too little. This calculator compares what the default treatment actually withholds against what you'd truly owe if both incomes were combined correctly, so you know which direction (if any) your specific situation points.
There are three real outcomes: if your main job alone already uses your full Personal Allowance and keeps you within the basic rate band, the default BR treatment on your second job is usually accurate. If your main job pays less than the £12,570 Personal Allowance, some of that allowance goes unused and the default treatment over-withholds. And if your combined income from both jobs pushes into the 40% higher-rate band, the flat 20% BR rate on your second job under-withholds that portion — a version of the same double-income stacking issue that shows up across every UK calculator in this category.
UK Second Job Tax Calculator Formula
Default Withholding = Tax(Job 1, Full Allowance) + (Job 2 × 20%)
Actual Tax = Tax(Job 1 + Job 2, Full Allowance)
How Is the UK Second Job Tax Calculator Calculated?
The default PAYE treatment applies your full £12,570 Personal Allowance and standard progressive bands to your main job in isolation, then taxes your second job entirely at the flat 20% basic rate with no allowance at all. The actual, correctly-combined tax treats both incomes as one total, applying the allowance once and the progressive bands to the full combined amount — this is what you'd truly owe if everything were assessed together, which is effectively what happens at year-end reconciliation (through Self Assessment or an HMRC coding adjustment) if the in-year withholding didn't match.
The gap between these two figures is exactly your over- or under-withholding: HMRC does eventually reconcile this either through a tax code adjustment, a Self Assessment return if you file one, or a P800 calculation — this calculator lets you see that gap in advance rather than being surprised by it.
UK Second Job Tax Calculator Example
A £8,000 main job (below the Personal Allowance, leaving £4,570 unused) plus a £15,000 second job: the default BR treatment withholds about £3,000, but the actual combined tax is only about £2,086 — an over-withholding of roughly £914/year, since the unused allowance from the main job isn't being applied anywhere.
A £25,000 main job plus a £10,000 second job: both figures match exactly at £4,486, since the main job alone already fully uses the Personal Allowance without pushing combined income into a higher band — the default BR treatment gets this one right.
A £45,000 main job plus a £20,000 second job: combined income of £65,000 pushes £27,300 into the 40% band, but the flat 20% BR code on the second job doesn't reflect that — the default withholding of £10,486 falls about £2,946 short of the actual £13,432 owed.
How to Use the UK Second Job Tax Calculator
Step 1
Enter your main job salary and your second job salary.
Step 2
Review whether the default BR treatment on your second job over-withholds, under-withholds, or gets it right.
Step 3
Use the specific gap figure to decide whether to contact HMRC about your tax code.
Benefits
- Shows which of three real outcomes applies to your specific two-job situation — correct, over-withheld, or under-withheld.
- Quantifies the exact gap so you know what to expect at tax reconciliation time.
- Uses verified 2026/27 HMRC Income Tax bands and Personal Allowance.
- Clarifies a commonly misunderstood assumption about how second jobs are taxed.
- Free, instant, and runs entirely in your browser.
Common UK Second Job Tax Calculator Scenarios
Scenario 1
Checking whether a new second job's BR tax code is treating you fairly.
Scenario 2
Deciding whether to ask HMRC to split your Personal Allowance across two jobs.
Scenario 3
Understanding whether you're likely to owe extra tax or receive a refund at year-end.
Scenario 4
Planning cash flow around an expected under- or over-withholding gap.
Scenario 5
Explaining to someone starting a second job why their new payslip looks the way it does.
Understanding Your Result
A positive gap means you're currently paying more tax than you actually owe across both jobs combined — this typically resolves itself as a refund, either automatically through a tax code adjustment or when you file a return. A negative gap means you're currently paying less than you actually owe, which usually catches up with you as extra tax due, either through a coding notice, a Self Assessment bill, or a P800 calculation from HMRC.
A result close to zero means the default system is working roughly as intended for your specific combination of incomes — no action needed.
Tips
- If you're being consistently over-withheld because your main job doesn't use your full allowance, you can ask HMRC to reallocate some of your Personal Allowance to your second job instead of the default BR code.
- If you're being under-withheld because combined income reaches the higher rate band, consider asking HMRC to apply a D0 code to your second job instead of BR, which would withhold at 40% and more closely match reality.
- This calculator shows an annual snapshot — if either salary changes during the year, your actual over/under-withholding will shift too.
- HMRC does eventually catch and correct significant under- or over-withholding, but proactively adjusting your tax code avoids a surprise bill or a slow-to-arrive refund.
- Keep an eye on your P60 or use your personal tax account on gov.uk to check both jobs' tax codes match what you'd expect from this analysis.
Common Mistakes
- Assuming BR always means your second job is being taxed correctly, when it depends entirely on your specific income split.
- Not realizing that a low-paying main job can leave real, unused Personal Allowance that a default BR second job misses out on.
- Being surprised by an under-withholding bill without realizing combined income had crossed into the 40% band.
- Not contacting HMRC to adjust tax codes even after noticing a persistent gap, letting it accumulate over a full tax year.
- Confusing this two-PAYE-jobs scenario with combining PAYE and self-employed income, which works differently.
Frequently Asked Questions
Why does my second job have a BR tax code by default?
HMRC assumes your Personal Allowance is already being used by your main job, so your second job is taxed at a flat 20% with no allowance applied — a reasonable default assumption that isn't always accurate for every specific income combination.
Can I ask HMRC to change my second job's tax code?
Yes — if this calculator shows a meaningful over- or under-withholding, you can contact HMRC (often through your personal tax account) to request your Personal Allowance be split between jobs, or a more accurate code like D0 applied to your second job if you're a higher-rate taxpayer.
Will HMRC automatically fix an incorrect second job tax code?
Often eventually, yes — through an annual reconciliation (a P800 calculation) or if you file a Self Assessment return, but this can take time, and proactively requesting a code change is usually faster than waiting for automatic correction.
What if I have three or more jobs?
This calculator only supports two jobs — with more than two, the same principles apply but the calculation becomes more complex since only one job can hold your main Personal Allowance at a time.
Does National Insurance work the same way across two jobs?
National Insurance is generally calculated separately for each job against its own threshold, unlike Income Tax's shared Personal Allowance — this can mean paying more combined National Insurance across two jobs than you would from the same total income at one job, a different issue from what this calculator addresses.
Is it always better to consolidate into one job if possible?
Not necessarily for tax reasons alone — this calculator only addresses the PAYE withholding mechanics; the decision to hold one job versus two involves many other factors beyond just tax withholding accuracy.
What if my second job is actually my higher-paying one?
For this calculator's purposes, "main job" simply means whichever job is currently holding your Personal Allowance (tax code 1257L) — enter your jobs into the corresponding fields based on which one actually has the standard code versus the BR code, regardless of which pays more.
Does this apply to a job and a pension both being taxed through PAYE?
The same general mechanics apply, since a pension in payment is also taxed through PAYE with its own tax code — you can use this calculator by treating the pension similarly to a "job" for this comparison.
What if one of my incomes is self-employment instead of a second PAYE job?
This calculator specifically addresses two PAYE-taxed jobs — combining PAYE employment with self-employment income works differently, since self-employment tax is assessed through Self Assessment rather than a second job's tax code.
Does the order I enter my two jobs matter?
Yes — enter the job that currently holds your standard tax code (1257L) as "main job," and the one on BR as "second job," since the calculation specifically models that asymmetric default treatment.
Will this affect my student loan repayment too?
Student loan repayment calculations have their own separate rules for multiple PAYE jobs, generally assessed similarly to Income Tax's combined approach at year-end — not modeled in this specific calculator, which focuses on Income Tax.
Can I share my second job tax check as an image?
Yes — tap Share and, on supported devices, your result is shared as a branded image card, not just a text link.
References
Important Information
This calculator provides estimates for informational purposes only and is not tax advice. Uses confirmed 2026/27 HMRC Income Tax bands and Personal Allowance (England/Wales/Northern Ireland); does not model National Insurance, student loan repayment, or Scottish tax codes. Confirm your specific tax code situation directly with HMRC.
Last updated: August 2026