Next 3 , 6, 9, 12 months

SQL SERVER:

DECLARE @3MB DATE = CAST(DATEADD(dd,-(DAY(GETDATE())-1),GETDATE()) AS DATE),

@3ME DATE = CAST(DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,2,GETDATE()))+1,0))AS DATE),

@6MB DATE = CAST(DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,2,GETDATE()))+1,0)AS DATE),

@6ME DATE = CAST(DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,5,GETDATE()))+1,0))AS DATE),

@9MB DATE = CAST(DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,5,GETDATE()))+1,0)AS DATE),

@9ME DATE = CAST(DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,8,GETDATE()))+1,0))AS DATE),

@12MB DATE = CAST(DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,8,GETDATE()))+1,0)AS DATE),

@12ME DATE = CAST(DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,DATEADD(mm,11,GETDATE()))+1,0))AS DATE)

SELECT @3MB AS TMB, @3ME AS TME, @6MB AS SMB, @6ME AS SME, @9MB AS NMB, @9ME AS NME, @12MB AS TWMB, @12ME AS TWME


SSRS:

=Today.AddDays(1-Today.Day) -- 1st day of current month
=Today.AddDays(1-Today.Day).AddMonths(3).AddSeconds(-1) -- end of 3rd month from today
=Today.AddDays(1-Today.Day).AddMonths(3) -- begin of 4th month from today
=Today.AddDays(1-Today.Day).AddMonths(6).AddSeconds(-1) -- end of 6th month from today
=Today.AddDays(1-Today.Day).AddMonths(6) -- begin of 7th month from Today
=Today.AddDays(1-Today.Day).AddMonths(9).AddSeconds(-1) -- end of 9th month from today
=Today.AddDays(1-Today.Day).AddMonths(9) -- begin of 10th month from today
=Today.AddDays(1-Today.Day).AddMonths(12).AddSeconds(-1) -- end of 12th month from today