Monthly Budgets is now deprecated, and no longer maintained. You can either move to Bureaucracy
Or JoeBostic on Github made a mod inspired by Monthly Budgets a while ago called Space Program Funding
If anyone would like to take over Monthly Budgets, ping me a PM and we'll chat.
This mod does what it says on the tin... it introduces a budget system to Career Mode KSP.
Unlike some other budget mods, whi