The main source of income over time in Imperator are Taxes and Commerce.
Tax income of a city is primarily based on how many slaves and tribesmen you have in that city. Then of course there are several modifiers that affect it, like access to trade-goods, stability, ministers, and some factions when in power may increase your tax income. Each slave provides 0.03 gold, which is modified multiplicative with output efficiency and number of slaves and rounded down to the second digit. Similarly, each tribesman provides 0.015 gold multiplied by the output efficiency.
Commerce income is determined by a city's commerce value multiplied by it's commerce modifiers. Commerce value can come from two sources, citizens and trade routes. Citizen's produce a certain commerce value per population based on their happiness. Trade routes add a base commerce value that is divided by the number of cities in the province with each city receiving the same share. Both these commerce values are then multiplied by the commerce modifiers to give you the city commerce income.
Every office or job in your country has a defined wage. A wage is always a certain percentage of your income, how high dependent on the office it is for. Character Corruption further modifies the wage of office holders.
There are also various economic policies that affects your income and expenses on a country level.
Modifies income from taxes.
|Lax Taxation||-1 National Unrest||-25% National Tax|
|Harsh Taxation||+25% National Slave Output||-20% Research Points|
Modifies income from Commerce.
|Free Trade||+1 Province Import Routes||-15% National Commerce Income|
|Transaction Taxation||+15% National Commerce Income||+2 Slaves Needed for Surplus|
Modifies how much you expect your subject states to pay to you.
|Lax Tribute||Subject Opinion +50||-33% Tribute Income from Subjects|
|Extortive Tributes||+25% Tribute Income from Subjects||Subject Opinion -100|
The Monthly cost for all troops in your country.
|Decreased Pay||-33% Army Maintenance Cost||-80% Army Morale|
|Increased Pay||+10% Army Morale||+50% Army Maintenance Cost|
The Monthly cost for all the ships of your country.
|Decreased Pay||-50% Naval Maintenance Cost||-80% Naval Morale|
|Increased Pay||+10% Naval Morale||+50% Naval Maintenance|
The cost to maintain all forts of your country.
|Ignored Garrisons||-25% Fort Maintenance||-50% Garrison Size and Fort Defence|
|Extortive Tributes||+10% Garrison Size and Fort Defence||+25% Fort Maintenance|
How much the wage of offices and jobs is increased or decreased.
|Decreased Pay||-25% Monthly Wages for all Characters||-0.5 Monthly Loyalty|
|Increased Pay||+0.1 Monthly Loyalty||+50% Monthly Wages for all Characters|
Should your country at any time find itself running a deficit this will result in a number of bad things. These can be seen at the bottom of the screen under the balance itself. Some of these events may well help you turn your economy around, but none of them come without a high price to be paid in some form.