Finance · Topic 2 of 5
Deductions & Tax (Income Tax, National Insurance, Pensions)
Theory
The Golden Rule: deductions questions test your ability to follow the exact sequence. You must remember that National Insurance is always calculated on a person’s salary before deductions such as pension contributions.
1. National Insurance & Tax Bands
Income Tax and National Insurance are rarely calculated as a simple, single percentage. Instead, you are given tables with thresholds or "bands".
- Up to the first threshold: You pay 0%.
- The middle band (e.g., 12%): You only pay this percentage on the portion of your salary that falls between the two stated values. To find this, subtract the lower number from your salary (or from the upper limit, if your salary exceeds it).
- The upper band (e.g., 2%): You only pay this percentage on the amount of your salary that is strictly over the final threshold.
2. Pensions
A workplace pension is a retirement fund. In the exam, you will usually be asked to calculate a pension contribution as a flat percentage of the gross annual salary.
3. Calculating Net Pay (Weekly/Monthly Conversions)
To find a person's Net Pay, you must subtract all three major deductions (Income Tax, National Insurance, and Pension) from their Gross Pay.
- Exam questions often give you annual figures but ask for the weekly net pay.
- You must calculate the total annual net pay first, and then divide by 52 to find the weekly amount.
⚠️ Common Examiner Traps
- The "Pre-Deduction" Trap: a question will often list the pension deduction first in the text, baiting you into subtracting it from the gross pay before calculating National Insurance. National Insurance is always calculated on the gross pay before pension deductions are taken.
- The "Whole Salary" Trap: When calculating tax or National Insurance using bands, candidates often lose marks by applying the 12% rate to their entire salary, rather than just the slice of money that falls within that specific band.
- The "4 Weeks in a Month" Trap: If a question asks you to convert between weekly and monthly pay, do not multiply or divide by 4. You must always use the annual figure as a bridge (multiply by 52 weeks, then divide by 12 months, or vice versa).
Worked examples
Example 1
Mark has an annual salary of £46,500. National Insurance is calculated on a person's salary before deductions.
Annual National Insurance Rates
- Up to £12,570: 0%
- From £12,570 to £50,270: 12%
- Over £50,270: 2%
Calculate Mark's annual National Insurance payment. (3 marks)
Step 1: Look at the first band. Mark pays 0% on the first £12,570.
Step 2: Look at the second band. Mark earns £46,500, which falls inside this band. Subtract the bottom threshold to find the taxable slice.
Step 3: Calculate 12% of this slice.
Step 4: Look at the third band. Mark does not earn over £50,270, so he pays £0 here.
Final Answer: Mark's annual National Insurance payment is £4,071.60.
Example 2
Chloe has an annual salary of £34,800. She pays 6.5% of her annual salary into her workplace pension. Her annual income tax is £4,120.50. Her annual National Insurance payment is £2,667.60. She is paid in 52 weekly payments.
Calculate Chloe's weekly net pay. (4 marks)
Step 1: Calculate her annual pension contribution based on her gross salary.
Step 2: Calculate her total annual deductions by adding the pension, tax, and National Insurance together.
Step 3: Subtract the total deductions from her gross salary to find her annual net pay.
Step 4: Divide her annual net pay by 52 to find her weekly net pay.
Final Answer: Formatted correctly as money, her weekly net pay is £495.19.