A signing bonus is usually paid with a clawback: leave within a defined period, typically one or two years, and you repay it, often the gross amount rather than what actually reached you. It costs the employer nothing structurally because it does not raise the salary band, which is exactly why it is offered when a base increase is refused — and why accepting one instead of base is usually the worse trade.
Why employers prefer them
A signing bonus is a one-off cost outside the salary band. It does not raise the band, does not compound into future raises, does not increase the bonus at target or the retirement match, and does not have to be matched for anyone else at the same level.
Base does all of those things. That is why base is harder to move and why a signing bonus is frequently offered as the consolation.
The arithmetic over three years
A signing bonus is paid once. An equivalent addition to base is paid every year, compounds through every subsequent percentage raise, and increases the match and the bonus with it. Even over a short tenure, base wins comfortably unless the signing bonus is several times the base difference.
Which is the argument to make when one is offered instead of the other: not that the bonus is unwelcome, but that you would take a smaller number on base.
The clawback, and the part that catches people
Most signing bonuses are repayable if you leave within a stated period. Read two things carefully. Whether repayment is pro-rated or all-or-nothing at the boundary — the difference at month thirteen of a twenty-four month term is substantial. And whether you repay the gross or the net.
Repaying gross is common and it means repaying money you never received, because tax was withheld at payment. Recovering that withholding is possible and awkward, and the cash flow is entirely yours to manage.
When a signing bonus is genuinely the right answer
When it is compensating for something specific and one-off: equity you are forfeiting by leaving before a cliff, a bonus you will miss by moving mid-year, relocation costs. In those cases it is matched to a real one-time loss and base would be the wrong instrument.
Ask for it explicitly on that basis and the number is easier to justify, because it is anchored to something checkable.
What to establish before accepting
The repayment period and whether it pro-rates. Gross or net. Whether it is forfeit if you are made redundant, which is the case that matters most and is often silent in the letter. And when it is paid, since first-paycheck and after-ninety-days are both common and they are not the same offer.
Common questions
Do I have to repay a signing bonus if I leave?
Usually, within a stated period. Check whether repayment pro-rates or is all-or-nothing at the boundary, because the difference near the end of the term is substantial.
Do I repay the gross or what I received?
Gross is common, which means repaying money you never received because tax was withheld. Recovering that withholding is possible and awkward, and the cash flow is yours.
Why do employers offer a bonus instead of base?
Because it sits outside the salary band. It does not compound into future raises, does not raise the match or the bonus at target, and does not have to be matched for others at the level.
Should I take a signing bonus or more base?
Base, almost always, unless the bonus is several times the base difference. Base is paid every year and compounds through every subsequent raise.
What if I am made redundant during the clawback period?
Check the letter specifically. Many are silent on it, and it is the case most likely to arise and least likely to be addressed.