The prospective housing payment would be comfortably manageable with your expected new salary. However, the higher amount has not yet actually been agreed or is available. For the purchase decision it therefore matters what the plan looks like until then and what happens if the change does not occur. This case examines a dependency; it does not assess employment law claims or creditworthiness from the bank's perspective.
Calculate the transition as a separate phase
Write down current income, concrete later changes already proven, and personal hopes separately. An upcoming discussion about a raise is a different basis than an amount already verifiably confirmed with a date. Even with confirmation, the question remains when the money will actually be available for the respective payments.
First prepare the calculation with today's income. All assumed future ownership expenses are already taken into account in it, insofar as they belong to that period. This makes it visible whether the first months would be covered even without the hoped-for additional amount.
The hypothetical shortfall
Under the assumptions chosen here, 250 euros are missing monthly after the planned purchase. A hoped-for income increase of 400 euros is expected to start after six months. If it becomes available as assumed, the first phase would initially have to be covered from other means to the amount of 1.500 euros. After that, under the same assumptions, 150 euros would remain monthly.
If the additional amount instead only arrives after twelve months, the initial coverage gap increases to 3.000 euros. If the change fails to materialise entirely, the monthly undercoverage remains. These calculation variants make no claim about probability of occurrence. They show what the purchase decision would be economically dependent on.
A confirmation and a reserve serve different purposes
An available reserve can bridge the first phase, provided it is not also needed elsewhere. However, it does not turn an unconfirmed permanent improvement into regular income. Therefore show separately what balance would remain after the transition.
A possible additional part-time job or extra assistance is not automatically inserted into the unfavourable variant. New concrete grounds would be needed for that. Otherwise every identified gap is merely closed with a second hope.
Set the decision point in advance
Note which confirmed income basis you need for personal affordability and by when it would have to be in place for the planned process. Discuss the unresolved dependency openly in the financing advice. If the project would not be affordable without the change, that is a central unresolved prerequisite and not a small marginal note behind an attractive monthly payment.