moving year

The function is based on the Fiscal Year, meaning for example if it’s Aug 2020, it is FY2020; however, if it is, Oct 2020, it’s FY2021. What I am trying to figure out is a function that changes the year when the FY year changes.

For example, if I have Aug 2015 on cell B1 as my main input, then cell C1 is 2015. If I have Oct 2015 (see B4), then my cell C4 would be 2016.

Furthermore, if I have Aug 2013 on cell B6 as my main input, then cell C6 is 2013. If B8 is Nov 2014, then C8 is 2015.

This means that the fiscal year starts in October 1 of the current year and ends on September 30 of the following year. For example, FY15 is October 1, 2014 to September 30, 2015.

Please help. Thank you.