Loan

Loans is a way to borrow money from the population. They have no interest rate and current have no penalty for not being paid off.

The current account balance shown on the Inventory (F4) window is red when money is owed.

Credit limit

The credit limit for an avatar is depend on his/her reputation.

The exact math is:

credit limit = (reputation + 0.5) * 100000

This means that with a reputation of 0, it is still possible to loan up to 50k¢. But if the reputation is negative, it is not possible to make a loan at all.

Loaning

A loan must be made at a bank, and the city's citizen accounts most hold enough money.

Bank Money

Banks loan money from the citizen accounts of a city. An amount is held in reserve, so the citizens don't go bankrupt.

reserved amount = (population x 1000) + 1000

They will loan whatever remains after that.