Compare signing bonus with salary.
A signing bonus is a one-off payment usually taxed at marginal rates and tied to a clawback period, while a lower base salary is a permanent reduction. Comparing them requires spreading the net bonus across the clawback months and setting that against the monthly salary shortfall. A bonus that looks generous frequently fails to cover even the period during which you cannot leave without repaying it.
Bonus against a permanent salary shortfall
Net bonus = bonus x (1 - tax rate); monthly value = net bonus / clawback months; months offset = net bonus / (annual shortfall / 12); advantage = net bonus - monthly shortfall x clawback months
Tax treatment of signing bonuses and the enforceability of clawback clauses vary by jurisdiction and contract. Read the offer terms and take advice before relying on this comparison.
Because it is the minimum time you are committed for, so it is the right horizon for the comparison. A 24-month clawback means the bonus must beat 24 months of salary shortfall to be worth taking.
Usually as ordinary income at your marginal rate, and often with supplemental withholding that feels higher at the time. That is why the net figure, not the headline, is the one to compare.
When you need cash now — a relocation or a gap in earnings — or when the base is already at the top of the band and the bonus is the only remaining flexibility. Otherwise base salary is worth more, because it compounds through future raises and pension.