Find the answer. Then use your own numbers.
TaxDecod guides explain the rule; the product should do the work. Start with the tool that matches your problem, or search the source-backed guide library below.
Source discipline
Official rules first
Thresholds and rules link to HMRC, GOV.UK or Scottish Government sources. Calculator outputs remain clearly labelled as TaxDecod estimates.
I have a payslip
Upload it and break it down
Start with the actual document, then open a guide only for the line you need to understand.
I know my salary
Calculate take-home pay
Model region, pension and student-loan assumptions before reading the rules behind the result.
My tax code looks wrong
Decode the code first
Understand common UK tax-code structures and emergency markers before assuming payroll made an error.
Find the answer
Search by the problem you actually have
Use the library for rules and explanations; use the linked tools when you need your own numbers.
How Income Tax works in the UK
A 2026/27 guide to Personal Allowance, tax bands, PAYE, marginal rates and why crossing a threshold does not move your whole salary into a higher tax rate.
Reviewed 14 September 2026
National Insurance explained for UK employees
How employee Class 1 National Insurance works in 2026/27, including the £12,570 primary threshold, £50,270 upper earnings limit and standard Category A rates.
Reviewed 14 September 2026
UK tax codes explained
Understand 1257L, BR, D0, D1, 0T, K codes, Scottish and Welsh prefixes, and why your tax code can change the PAYE deducted from salary.
Reviewed 14 September 2026
How PAYE works in the UK
A practical guide to Pay As You Earn: how employers use pay, tax codes and payroll records to deduct Income Tax and National Insurance before wages reach your bank account.
Reviewed 14 September 2026
How to read a UK payslip
A line-by-line guide to gross pay, net pay, PAYE tax, National Insurance, pension, student loans, tax codes and year-to-date figures on a UK payslip.
Reviewed 14 September 2026
Gross pay vs net pay explained
Understand the difference between headline salary, taxable pay, deductions and the net amount that actually reaches your bank account.
Reviewed 14 September 2026
Take-home pay explained
What take-home pay means, the deductions that reduce gross salary, and why the amount in your bank account can change even when annual salary does not.
Reviewed 14 September 2026
How student loan repayments affect salary
Current 2026/27 Plan 1, Plan 2, Plan 4, Plan 5 and Postgraduate Loan thresholds, repayment rates and how payroll deductions change take-home pay.
Reviewed 14 September 2026
Salary sacrifice pension explained
How pension salary sacrifice can change gross cash pay, employer pension contributions, Income Tax, National Insurance and monthly take-home pay.
Reviewed 14 September 2026
How pension contributions affect take-home pay
Why a £100 pension contribution does not always reduce take-home pay by £100, and how net pay, relief at source, net pay arrangements and salary sacrifice can differ.
Reviewed 14 September 2026
Scottish Income Tax explained for 2026/27
The 2026/27 Scottish starter, basic, intermediate, higher, advanced and top tax bands, plus how Scottish tax differs from the rest of the UK salary calculation.
Reviewed 14 September 2026
The £100k tax trap explained
Why adjusted net income above £100,000 reduces the Personal Allowance, how the taper works to £125,140, and why the effective marginal Income Tax rate can become unusually high.
Reviewed 14 September 2026
How bonuses are taxed in the UK
Why cash bonuses are added to earnings, how PAYE Income Tax and Class 1 National Insurance apply through payroll, and why a bonus month can look heavily deducted.
Reviewed 14 September 2026
Emergency tax explained
What W1, M1, X and NONCUM mean, why emergency PAYE can appear after starting a job, and how to check whether payroll has enough information.
Reviewed 14 September 2026
Personal Allowance explained
How the £12,570 standard Personal Allowance works in 2026/27, how tax codes use it, and why adjusted net income above £100,000 can reduce it.
Reviewed 14 September 2026
Specific questions
Dig into the salary question you came with.
These focused guides complement the main library with salary targets, monthly tax, loan deductions and budgeting examples. Use the linked calculators whenever your circumstances differ.
Keep moving
Guides should end in a useful action
After you understand a rule, move into the salary calculator, payslip analyser, tax-code decoder or salary comparison rather than reading another article for the sake of it.