A taxpayer is an individual or entity that is required by law to pay taxes. Taxpayers are responsible for reporting their income, profits, or sales to the tax authority and for paying the taxes that are owed on that income.

For individual taxpayers, this usually includes filing an annual tax return and paying any taxes that are owed based on their income, deductions, and credits. Businesses, on the other hand, are typically responsible for filing quarterly or annual tax returns and paying taxes on their profits. Some businesses, such as sole proprietorships, may also be required to pay self-employment tax on their business income.

Taxpayers are also responsible for keeping accurate records and for reporting any changes in their income or tax situation that may affect their taxes. It's important to note that the definition of taxpayer can vary depending on the country and the type of tax. In some places, businesses may not be considered taxpayers for certain types of taxes, such as property taxes which are usually imposed on the property owners.