System Mechanics: Government and Taxes:

Almost every settled region that has an expansive government has a budget that is made up of either donations or, as is more often the case, collected taxes and fees.  There are a multitude of these as per the local, regional and higher laws, and any character within areas that have them is expected to properly deal with them or face consequences.  As such, most adventurers may find themselves having to sneak their gathered treasure to hidden caches rather than directly home in order to avoid paying, but getting caught may have higher penalties than just fees depending on the local laws.  Trying to keep taxes from a king, for example, may either make a character find themselves losing a prize possession worth more than the taxes and fees, a limb, a family member or even their own life.  The amount of tax per area is determined by the type of government, budgetary costs of said government for its own operation, budgetary costs of said government for public works and possibly pet projects, budget for military force, budget for civil defense, and other concerns.  An area that has no government has no taxes, but it also is ripe for a band of thieves to settle and do as they wish, or to be invaded and overwhelmed, or used as middle-ground between two warring parties.  Some fees must also be gathered in order to pay for damages to public property, loss of time while protecting public property, and often as preventatives to diminish common problems the area may have, such as drunken disorderly conduct, vandalism and other acts.  To determine the exact amount of tax and fees is impossible without either improvisation or determining a rate and types of fees ahead of time for a GM.  As all areas have different types of government and different needs for public works, the rate will fluctuate wildly, but below is some assistance (Note that not all governments are perfect examples of their type, but may be more suited to one description over another):

     In general, taxes on the most heavily taxed are at 4d20 percent maximum, 1d20 percent minimum, and scaling down by 5-10% per social class or tax bracket at minimum, 10-25% per social class or tax bracket at maximum.

     Anarchy: Government by none, no taxes, no fees, everyone for themselves.
     Argentocracy: Government by the wealthy, taxes and fees on all, but higher on lower class, less rights for lower class.
     Aristocracy: Government by nobility, taxes and fees on all but rulers, fluctuates on whims, those not of nobility have less rights.
     Democracy: Government by the majority, taxes and fees on all, equal rights if a citizen.
     Despotism: Government by one individual, high taxes and fees on rest, less rights for all others.
     Communism: Government by community, high taxes and fees on all, equal rights.
     Ergatocracy: Government ruled by the working class, taxes and fees on all, but higher on upper class, working class may have more rights.
     Gerontocracy: Government by the aged, taxes and fees on the young, more rights with age.
     Hoplarchy: Government by the military, high taxes and fees on civilians, less rights for civilians.
     Matriarchy: Government by females, taxes and fees on all, less rights for other genders.
     Patriarchy: Government by males, taxes and fees on all, less rights for other genders.
     Republic: Government by elected officials, taxes and fees on all, equal rights if a citizen.
     Socialism: Government by popular vote, high taxes and fees on all, equal rights if a citizen.
     Tetradarchy: Government by four individuals, taxes and fees on everyone else, less rights for all others.  (May also have other forms of numbered government ruling systems by similar names).
     Theocracy: Government by largest religious group, taxes and fees on all, less rights for those of other religions.