Would something like this get you started?

create table #temp (

Row_Ndb int,

Account_Nbr int,

Account_Name char(5),

Account_Desc char(3),

Begin_Date date,

End_Date date

)

insert into #temp values

(1, 1, 'test1', 'chk', '1/1/2012', '3/1/2012'),

(2, 1, 'test1', 'chk', '3/2/2012', '6/30/2012'),

(3, 1, 'test' , 'chk', '8/2/2012', '12/31/2012')

with cte

as

(

select row_ndb

, account_nbr

, account_name

, Account_desc

, Begin_date

, End_date

, row_number() over (partition by Account_Nbr order by begin_date) rownum

from #temp

)

select *

from

(

select cte1.*

, case when datediff(d,cte2.End_date,cte1.begin_date) > 2 then datediff(d,cte2.End_date,cte1.begin_date) else 0 end as DaysMissing

, case when datediff(d,cte2.End_date,cte1.begin_date) > 2 then dateadd(d,1,cte2.end_date) else null end as MissingBegin_Date

, case when datediff(d,cte2.End_date,cte1.begin_date) > 2 then dateadd(d,-1,cte1.Begin_date) else null end as MissingEnd_Date

from cte cte1

left join cte cte2

on cte1.account_nbr = cte2.account_nbr and cte1.rownum = cte2.rownum + 1

) source

where source.DaysMissing > 0

drop table #temp