I found out how to do it, the date_part function is essential for this.
select @location
,sum(x.amount) as Tot_amount
,sum(case when date_part('month', x.date) = 1 and date_part('year', x.date) = 2014 then amount end) as January_Tot
sum(case when date_part('month', x.date) = 2 and date_part('year', x.date) = 2014 then amount end) as February_Tot
left join this_table2 y
on x.no = y.no
where y.desc = 'INCOME' and x.date between '1/1/14' and current_date