As with taxes, subsidies can be levied on a specific or ad valorem basis. The most common product groups where export subsidies are applied are agricultural and dairy products.
Most countries have income support programs for their nation's farmers.
These are often motivated by national security or self-sufficiency considerations. Farmers' incomes are maintained by restricting domestic supply, raising domestic demand, or a combination of the two. One common method is the imposition of price floors on specified commodities. When there is excess supply at the floor price, however, the government must stand ready to purchase the excess. These purchases are often stored for future distribution when there is a shortfall of supply at the floor price.