15Meaning of volume coefficient

15  Meaning of volume coefficient  (1) In this section, for a relevant operation in which natural gas is measured by volume: base year means:  (a) if an election has been made in relation to the operation under section 54—the 2012‑13 year of tax; or  (b) otherwise—the year of tax in which the actual volume of project natural gas first exceeds the estimated average annual volume of project natural gas for the operation. Note: If the estimated average annual volume of project natural gas changes from one year of tax to another, the base year for the calculation of the volume coefficient may also change.  (2) The volume coefficient for a relevant operation in which natural gas is measured by volume in a year of tax (the current year) is:  VA means the actual volume of project natural gas for the current year. VB means:  (a) if the current year is before the base year—the estimated average annual volume of project natural gas; or  (b) if the current year is the base year—VA; or  (c) if the current year is after the base year—the amount worked out using the formula:      n means a year of tax, with the base year being year 1, the year after the base year being year 2, and so on.   N means the number of years of tax from the base year to the current year (inclusive).   Vn means the actual volume of project natural gas for year n.