I've added another save: "Östersunds FK - Negative Budget After Win".
The budgets are set immediately after the match this is saved at (assuming you win, since I think the budget is set upon winning the league).
In any case, the club has £41.5 million in the bank, but as soon as the budget is set, I have a -817k transfer budget, with a wage budget 6 times higher than my current spend. If you check the next season budget before the match, you can see that it's locked at 0, and the board always rejects attempts to alter it due to the current finances at the club. This happens every single season, regardless of the money available to the club.