In a market of price-taking firms, the market (inverse) supply curve is and the (inverse) demand curve is , where refers to price and refers to quantity. 'Tax burden' refers to how the tax on each unit sold is shared between producers and consumers. If the government imposes a per-unit tax on this market, then:
To determine the tax burden, we compare the absolute values of elasticities of supply and demand. The supply curve is less elastic, since a change in price leads to a smaller change in quantity supplied, than demand. Since the supply is less elastic than demand, firms will bear more of the tax burden.