currency, nor raise its own defence force. However, the federal parliament may only make laws for matters to which it has been specifically granted the ability to do so by Australia's Constitution. Therefore, the remaining powers remain the legal domain of each state parliament in turn. The Treasury Corporation of Victoria outlines that the Victorian Parliament's key responsibilities are: "education, public health, police and justice, transport, roads and railways, industry, mining and agriculture, public works, ports, forestry, electricity, gas, and water supply and irrigation." The parliament may levy its own taxes, however, income taxes have been the exclusive domain of the federal government for decades. The state government's chief means of revenue (outside of grants from the federal government) comes from a combination of payroll taxes, stamp duties on housing and vehicles and a portion of the goods and services tax that is divided amongst all states. The Victorian Government may never levy new taxes, nor spend funds unless it has been specifically authorised to do so by the parliament. It may spend funds raised by taxes from the federal government, although such spending must still be approved by the Victorian Parliament. Victoria has deferred its powers to the federal parliament over time as Australia has concentrated power into its federal government. This is most often done with the practice of "tied grants", whereby the federal government funds projects that are administered at a state level, such as road and rail, but these grants are only given on the condition that the Victorian Parliament also assents to preconditions laid out by its federal counterpart. The Parliament of Victoria is a bicameral legislature. It usually fulfils its legislative role by first proposing bills in the Legislative Assembly, and then reviewing them in the Legislative Council. Common practice is that the houses sit in staggered dates; the Assembly usually meeting first in order to pass bills that the Council later debates. These houses sit in separate chambers. The parliament also has the ability to amend Victoria's constitution, although this power is subject to strict requirements. All sections must be passed by an absolute majority of each house (currently 45 in the Assembly and 21 in the council), regardless of how many members are present in the chamber. Alterations to Victoria's Constitution made in 2003 stipulate that some sections may not be modified without a three-fifths majority of both houses, while others may