Using A UDF To Return Values For A Dynamic WHERE IN () Clause

Greetings,

I've search around quite extensively on the net and found a few examples that touch on this subject, but the only definitive one that seemed to solve this problem used a temp table in the UDF, which, to my knowledge, is impossible...

The problem is thus:
I want to create either a stored procedure or a user defined function to return a list of values I can intersperse to use in a WHERE AccountID IN (<values>). This way, if someone were to create a new stored procedure and they wanted to either only select accounts with those IDs or perform a NOT IN and use it to filter.

The Solution I'm attempting:
My idea is best represented in psuedo-code:
- Create a Function that stores all account Ids we relate to a particular account type, in this case, let's say accountsids "100, 101, 102, 407" are all accounts we want to consider "cash".
- The function would look something like:
CREATE FUNCTION CashAccountIDs()

RETURNS TABLE

AS

BEGIN
DECLARE TABLE @t1 (account INT)
INSERT INTO @t1 VALUES (100)
INSERT INTO @t1 VALUES (101)
INSERT INTO @t1 VALUES (102)
INSERT INTO @t1 VALUES (407)
RETURN @t1
END

Then I could call this function by doing something such as:

SELECT *
FROM Accounts
WHERE AccountId IN (dbo.CashAccountIds())

I would presumably do this for other collections of accounts as well, so that I would end up with say 5 functions I could call to filter various types of accounts.

Not too certain if I am approaching this the correct way or not, I've been receiving a myriad of errors trying different methods. If I use the function above it tells me "Must declare @t1", so I modified it so @t1 is declared in the RETURNS statement, and the syntax checks then work, but when I attempt to save the function it tells me "Cannot perform alter on fn_cashaccountids because it is an incompatible object type"

(The code I use to generate this error is:
CREATE FUNCTION fn_cashaccountids ()

RETURNS @t1 TABLE (i INT)

AS

BEGIN
INSERT INTO @t1 VALUES (100)
RETURN
END

Hopefully I've provided enough but not too much info to sift through, it seems to me this would be something encountered a bit before.

Any help is very much appreciated.

- Jeff