No need for CASE here at all.

SELECT Name,

Total = ISNULL(Salary,0) + ISNULL(Bonuses,0)

FROM dbo.YourTable

;

If you insist on ANSI/ISO code, you can replace ISNULL with COALESCE. I use ISNULL to make sure the datatype stays the same as the first operand and, over millions of rows, is a bit faster than COALESCE.

As a note for future posts, please read and heed the article at the first lik in my signature line below. Thanks.