Note that you need to create a new leave policy for this and will not be able to update any existing policy.
This is because both the accrual rules and the reset rules needs to be modified which will affect existing calculations.
In order to have a leave policy that accrues and resets basis financial year instead of calendar year, please follow the following steps:
Go to leave-> Policies and click Create Policy button
Enter the name, description and select leave type details in "Basic" step
In Accrual Rules step,
if the accrual frequency is monthly or weekly, then you can fill the necessary details and go to the next step
otherwise if accrual frequency is Quarterly, Half Yearly or Annually: you will see an question called: What is the start month of the cycle?
Here you may select "April" as the start month instead of the default "January". This will make the accrual cycle run from April to March for every year.
After filling the details, then go to the next step: Reset Rules
If the reset frequency is weekly or monthly, then there is no implication of Financial year cycle. So just fill the necessary details and create the policy
Otherwise if reset frequency is quarterly, half-yearly or annually, you will see the question: What is the start month of the reset cycle?
Fill April here instead of the default "January" in order to reset the cycle every financial year