Question 1

What is a tax code, and why might mine be wrong?

Accepted Answer

A **tax code** tells your employer or pension provider how much **tax-free income** to give you before deducting tax. It is issued by HMRC, applied by your employer, and it is wrong more often than people assume.

**How to read it.** The number is broadly your tax-free allowance **with the last digit removed** — so 1257L means roughly £12,570 of tax-free income for the year, spread evenly across your pay periods.

**The letters:**

**L** — the standard personal allowance.

**M** and **N** — marriage allowance received or transferred.

**BR** — all income taxed at basic rate with **no allowance**, normally used for a second job or pension where the allowance is used elsewhere.

**D0 / D1** — all income at higher or additional rate.

**K** — a code where deductions **exceed** the allowance, so income is added rather than relieved, typically for taxable benefits or untaxed income being collected.

**NT** — no tax.

**W1 / M1 / X** — an **emergency** code, operating on a non-cumulative basis: each pay period is treated in isolation rather than taking account of the year to date. This is what causes the classic large overdeduction on a first payslip in a new job.

**Why codes go wrong:**

**Starting a new job** without a P45, so the emergency code applies.

**Two jobs or a job plus a pension**, where the allowance is allocated between them and the split becomes wrong if earnings change.

**Benefits in kind** — a company car, private medical insurance — collected through the code, based on **estimates** that lag reality.

**HMRC estimating other income**, such as savings interest or dividends, from previous years.

**Unpaid tax from a previous year** being collected via the code.

**A change in circumstances** not reported.

**What to do.** Check your code on a payslip and in your **personal tax account**, where you can see the calculation and the assumptions behind it. **Contact HMRC directly** to correct it — your employer cannot change a code without instruction, so complaining to payroll achieves nothing. Overpayments are refunded, usually automatically after year end.

General information, not tax advice.

Question 2

How do inheritance tax thresholds work?

Accepted Answer

Inheritance tax (IHT) in the UK is charged on the value of an estate above a threshold when someone dies. The structure involves several allowances that interact, which is why the commonly quoted

Question 3

What is the difference between gross pay and net pay?

Accepted Answer

Gross pay is what you earn before anything is taken off — the figure in your contract and in the job advert. Net pay is what actually reaches your bank account after deductions. The gap is often

Question 4

What does National Insurance actually pay for?

Accepted Answer

National Insurance (NI) is a UK contribution paid by employees, employers and the self-employed. It funds specific contributory benefits and the NHS — and the relationship between what you pay and

Question 5

Who actually has to file a self assessment tax return?

Accepted Answer

Anyone whose income is not fully taxed at source or whose circumstances fall into defined categories — and the obligation is yours to identify, which is the part that catches people out. Nobody

Question 6

What is pension auto-enrolment?

Accepted Answer

A UK system requiring employers to automatically put eligible staff into a workplace pension and contribute to it — with the employee opted in by default and free to leave. Why it exists. Voluntary

Question 7

What is capital gains tax, and when does it apply?

Accepted Answer

Capital gains tax (CGT) is tax on the profit made when you dispose of an asset that has risen in value — not on the amount you receive, and not on the asset itself. The core idea. Gain equals

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