How can force SQL DateDiff function to stop rounding up?

I am working on a query that tries to count from an exact date to an exact date. Today is 2/16/2022. Between 6/30/2020 and 2/16/2022 19 months have gone by. My DateDiff query returns 20? How can I force DateDiff function to return 19?

select datediff(month, '6/30/2020', getdate()) 

Answer

Here is the solution that worked for me.

declare @start date 
declare @end date
set @start = '6/30/2020'
set @end = '2/16/2022'
select datediff(month, dateadd(day, -day(@start)+1, @start), dateadd(day, -day(@start)+1,@end))

link to fiddle