Two salaries compare honestly only after tax. £38,000 against £42,000 looks like a £4,000 gap; in 2026/27 it is £2,880.00 of actual money, £240.00 a month: because every extra pound between those figures is taxed at the marginal rate, not the average one. Run both offers through the calculator this page links and compare the two nets; the sections below cover the traps in between.
Marginal rates decide the gap, not average rates
Between £38,000 and £42,000 each extra pound loses 28% (20% tax, 8% NI), so the gap keeps 72% of itself. Step across the £50,270 line and the marginal rate becomes 42% (40% tax, 2% NI): £50,000 to £55,000 is a £5,000 gross rise but only £2,937.80 net. The steeper the marginal band the rise lands in, the more two similar-looking offers converge after tax: always price the GAP at the marginal rate before deciding it is worth a longer commute.
Put both offers on the same basis first
Same hours (convert to full-time equivalents if not), same pension treatment (a 5% employee contribution with 8% from the employer can be worth more than £2,000 of gross elsewhere), and the same extras counted: car allowance is taxed as pay, most benefits in kind are taxed via your code, and location weighting is just salary. A bonus is pay in the year it lands, taxed at your marginal rate then, so weight a "up to 10%" bonus by how often it is actually paid.
A worked comparison, end to end
Offer A: £42,000, no pension match beyond the minimum. Net £33,759.60, or £2,813.30 a month. Offer B: £38,000 plus an employer pension contribution 4 points higher. Net £30,879.60 (£2,573.30 a month), but with £1,520.00 a year more going into the pension at no cost to take-home. On money-today A wins by £2,880.00; on total compensation the gap is nearly closed. The right answer depends on which pound you value: this page's job is to make both pounds visible.
Questions people ask about compare two salaries
Should I compare monthly or annual figures?
Either, consistently: the monthly net is the annual ÷ 12 for salaried pay. Comparing one offer's monthly against the other's four-weekly is the classic error.
How do I compare a salary against a day rate?
Multiply the rate by realistic billed days (around 220), subtract the costs an employee never pays, then tax what is left. The day-rate page linked from the answers index works this fully.
Does a salary just above £50,270 beat one just below?
Yes in net terms (more gross is always more net), but only at 58p per extra pound. £51,000 keeps just £617.80 more than £50,000.