Return SUM That Is Not 0?

I have this table that contains transactions for a specific client and some clients, when I total the transactions, have a zero balance.

I want to be able to filter those clients out, only show the ones that have open balances.

Here's an example:

DECLARE @T1 TABLE( CODE VARCHAR(6), ITEM INTEGER, AMOUNT INTEGER)
INSERT INTO @T1
VALUES
('ABC',4001,110),
('ABC', 4001, -110),
('ABC',4002,-5.5),

[code]....

If you look at the table, client ABC has a lot of transactions but if I SUM them the balance is 0, same with client GHI. The only row that show show on my query is client DEF.

I am trying to do something like this:

select *
from @T1
having Code in ( SELECT code
from @T1
group by code
having SUM(amount) <> 0)

but I get an error.