All other normal income is computed monthly, and does not go to the treasury unless directed there via the spending sliders. Rather, it accumulates in separate "accounts" which raise technology or stability once a sufficient amount has been "banked".
There are two sources of monthly income. Province income accrues to a country by virtue of owning provinces. (Looting is a special case of province income, based on army presence in enemy-owned provinces.) Trading income accrues to countries based on the presence of their merchants in centers of trade. Combined, these two sources are monthly income.
Monthly income may be directed into technology, stability, or the treasury, using the spending sliders on the budget screen.
Direct investment is a kind of monthly "income" that is added directly to a particular technology or stability. All types of direct investments are fixed in destination, and cannot be redirected using the spending sliders or any other means.
There are a three sources of direct investment:
- monarch investments, based on the monarch's military and administrative skills:
- the neighbor bonus, added directly to each technological field.
- manufactories invest directly into a particular technological field (or stability for FAAs).
There are also two sources of direct disinvestment, which lower investment rates. They are:
- the effect of war exhaustion on stability investment
- the effect of trade embargoes on trade technology investment
Although net rates of investment may be negative, negative investment rates cannot drop your technological level or stability. They can only peg your accumulated investment in a field at zero.
Income From Events
Events can also produce income, although unpredictably. Random events exist which give you money, in addition to the many that cost you money. Also, some random events give one-off investments into various tech fields.