impose taxes or fees on the privilege of carrying on a particular business or maintaining a particular professional certification. These licensing or occupational taxes may be a fixed dollar amount per year for the licensee, an amount based on the number of practitioners in the firm, a percentage of revenue, or any of several other bases. Persons providing professional or personal services are often subject to such fees. Common examples include accountants, attorneys, barbers, casinos, dentists, doctors, auto mechanics, plumbers, and stockbrokers. In addition to the tax, other requirements may be imposed for licensure. All 50 states impose a vehicle license fee. Generally, the fees are based on the type and size of the vehicle and are imposed annually or biannually. All states and the District of Columbia also impose a fee for a driver's license, which generally must be renewed with payment of fee every few years. User fees Fees are often imposed by governments for use of certain facilities or services. Such fees are generally imposed at the time of use. Multi-use permits may be available. For example, fees are imposed for use of national or state parks, for requesting and obtaining certain rulings from the U.S. Internal Revenue Service (IRS), for the use of certain highways (called "tolls" or toll roads), for parking on public streets, and for the use of public transit. Tax administration Taxes in the United States are administered by hundreds of tax authorities. At the federal level there are three tax administrations. Most domestic federal taxes are administered by the Internal Revenue Service, which is part of the Department of the Treasury. Alcohol, tobacco, and firearms taxes are administered by the Alcohol and Tobacco Tax and Trade Bureau (TTB). Taxes on imports (customs duties) are administered by U.S. Customs and Border Protection (CBP). TTB is also part of the Department of the Treasury and CBP belongs to the Department of Homeland Security. Organization of state and local tax administrations varies widely. Every state maintains a tax administration. A few states administer some local taxes in whole or part. Most localities also maintain a tax administration or share one with neighboring localities. Federal Internal Revenue Service The Internal Revenue Service administers all U.S. federal tax laws on domestic activities, except those taxes administered by TTB. IRS functions include: Processing federal tax returns (except TTB returns), including those for Social Security and other federal payroll