The basis of both taxation and citizenship is the poll tax. In theory, everyone who lives within the borders of a kingdom will pay the poll tax, which is usually very small (the traditional rates are 1 pence for an adult and a half-pence for a child). The poll tax is collected at a local level (such as the village, city block, or private estate) at the end of the year, before the harvest. As each person pays their poll tax, their address and profession are noted on the local Roll. This information is used to determine any other appropriate taxes (such as rent or land tax).
Payment of the poll tax and listing on the Roll is a guarantee of citizenship, and thus provides certain basic legal rights. If you try to obtain citizenship papers (so that you can travel in other kingdoms without having to pay their poll tax, for instance), the local authorities will check the Roll before issuing them.
The principal advantage of citizenship is that you are protected by the laws of the kingdom. Without this protection, it can be very dangerous to own property or possess disposable assets. If you are in another kingdom, proof of your citizenship usually entitles you to the legal rights and concessions enjoyed by foreigners. Because most people who travel and have citizenship papers are well-to-do and respectable, those who do not have papers are often considered disreputable and suspected of being criminals.
Other annual taxes include the land taxes, commercial taxes, and physical service (usually in the army, but sometimes working on public projects or communally owned property, like roads or canals). Custom duties are levied at major border crossings and at commercial ports, and traders receive papers to show that these duties have been paid. In some kingdoms the crown has a monopoly on certain trade goods, such as salt, precious metals, and alcohol, and traders may have to purchase the right to trade in that monopoly or forfeit their goods.