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Keith So
Keith So

Posted on • Originally published at boring-math.com

3 UK Money Checks I Run Before Saying Yes to a Pay Rise

3 UK Money Checks I Run Before Saying Yes to a Pay Rise

Most salary conversations focus on one number: gross pay.

But when your pay crosses certain UK thresholds, your effective gain can be much smaller than expected.

I keep a simple checklist and run the same three calculations every time I get an offer, raise, or contract change.

1) Check for the GBP 100k tax trap first

In the UK, your Personal Allowance is reduced by GBP 1 for every GBP 2 earned above GBP 100,000.

That means in the GBP 100k-GBP 125,140 range, many people face an effective 60% marginal rate (before National Insurance and student loan effects).

So if your salary goes from GBP 99,000 to GBP 109,000, the headline increase can feel great, but the take-home uplift can be underwhelming.

Use this first:

Quick sanity check

If a raise puts you just into that band, options like pension salary sacrifice can sometimes improve outcomes more than a straight cash increase.

2) Model student loan repayments on the new salary

Many people estimate repayments with rough percentages and get it wrong.

For Plan 2 borrowers, repayments are based on income above the threshold, so higher salary usually increases monthly deductions immediately.

Before accepting a raise, I test both scenarios:

  • current salary
  • proposed salary

Then compare annual repayment difference:

This prevents the classic "I got a raise but my payslip barely moved" surprise.

3) Convert the raise into real (inflation-adjusted) terms

A 5% raise in a 4% inflation environment is not a 5% improvement in buying power.

Run a quick real-value check:

If your nominal pay is up but real pay is flat, that changes how you evaluate the offer - and how hard you negotiate non-cash benefits.

A practical decision framework

When I compare two offers (or old vs new salary), I track four values:

  1. Gross salary difference
  2. Net annual take-home difference after tax + loan effects
  3. Pension impact (especially if salary sacrifice is available)
  4. Real-terms gain after inflation

Only then do I decide whether the raise is genuinely meaningful.

Why this matters

Most people don't need more financial theory - they need a faster way to avoid bad assumptions.

That's why I built these calculators: quick, no-signup checks you can run in 2 minutes before making a decision.

No signup. No email capture. Just math.

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