You can alter your budget allocation by answering issues. For example, issues with religion-based options will often increase your religion budget, issues about education can increase or reduce the education budget, environmental protections can increase environment budget while hitting commerce, and so on. The answers you give to the 8 questions on the nation creation screen also affect your budget.
Also, if you’re in the WA, then GA resolutions also affect your nation, however I’m not sure how many of them can modify your budget.
In its majestic equality, the law forbids rich and poor alike to sleep under bridges, beg in the streets and steal loaves of bread.