Arcane Empire II
The basic campaign assumes characters work for The Firm. This need not be the case and a fringe based campaign will have much different finances than a city campaign.
Under the general assumption characters are assumed to spend the down time between sessions (1 session per month is standard) doing smaller jobs for The Firm which maintain the character’s lifestyle (appropriate to their best skill).
It is also assumed characters have 10 days of discretionary time per month which can be used for training, enchanting, or earning extra income.
If used for income take the character’s best skill in pips, square the result and multiply by the number of days dedicated to extra income (1-10).
3D = 9 pips, 9 × 9 = 81 credits a day (81-810).
7D+2 = 23 pips, 23 × 23 = 529 credits a day (529-5,290).
As a side note the Arcane Empire has a 50% tax rate (all income made or all profit if making items). They do not have a property tax though, so taxes only have to be paid on an item once unless it changes owners.