In systems that use constituencies, apportionment or districting defines the area covered by each constituency. The United States Constitution requires a decennial census for the purpose of assuring fair apportionment. By their nature, rules for allocation and apportionment of expenses may become complex. Some states tax resident corporations on nonbusiness income regardless of apportionment. The Alabama Legislature is in charge of apportionment and redistricting in Alabama. A Commission on legislative apportionment was written into the 1963 state constitution. Pursuant to this apportionment, the constituencies are formed. Wages fluctuated significantly based on the congressional apportionment for that year. Ultimately, however, its main contribution was in determining the apportionment of the Senate. House districts are redistricted by the Arkansas Board of Apportionment. No repeal of the Land Apportionment Act. The law is silent on the rules governing the apportionment of loss. The basis of apportionment has also been litigated. Each state then draws single-member districts to conform with the census apportionment. HMRC does not prescribe any particular apportionment method.