Two balances, one wallet, and an ordering rule you did not choose
Accepting a promotion usually leaves an account holding two different kinds of money that look identical on screen: funds you deposited, which are yours, and promotional funds, which are conditional. Which of the two is consumed when you place a stake is set by the operator's rules, and it is the mechanism that determines whether opting in was a reversible decision. If your own money is spent first, you have committed it before the promotional funds have done anything. If the promotional funds go first, they can be exhausted while your deposit is still intact. Same offer, same account, opposite consequences β and almost nobody checks which one applies before clicking accept.
What follows from the ordering rule
These consequences are mechanical. They follow from the rule itself and do not depend on how any particular session goes.
It decides whether you can leave
Withdrawing while an obligation is outstanding often forfeits what remains of the promotional funds. Which balance is standing between you and the exit is set by the ordering rule.
The interface may not separate them
A single displayed total can contain both kinds of money. Where the account area shows a breakdown, that breakdown is the thing to look at before every decision, not the headline figure.
It changes what a cap applies to
A ceiling written against winnings from promotional funds needs a rule about which funds were in play. The ordering rule supplies it, which is why the two clauses have to be read together.
Ask before you deposit, not after
This is a factual question with a definite answer that the operator can give you in writing. It costs one message and it is unanswerable once the stakes have been placed.
Questions we get asked
Can I just withdraw my own deposit and abandon the bonus?
Sometimes, and the terms will say. A common structure treats a withdrawal made while a promotional obligation is outstanding as cancelling the promotion, forfeiting the remaining promotional funds and any winnings attributed to them. That may be a perfectly acceptable outcome to you, but it is a decision worth making deliberately rather than discovering at the point you try to take money out.
Why is this not simply a setting I can choose?
Because it is part of the economics of the offer rather than a preference. If customers could always stake the promotional funds first and retain their own deposit intact, the cost of running promotions would change substantially. Treating it as a term of the deal rather than a configuration explains why you will not find a toggle for it.
How do I find out which rule applies to me?
Look in the general account or bonus terms for language about the order in which funds are used, or how a stake is allocated between real and bonus balance. If the document is silent or you cannot tell, ask support directly and keep the reply. A written answer is also the thing you would need later if the account behaved differently from what you were told.