There is no minimum income requirement to sponsor a spouse/partner or dependent child (who has no dependent children of their own). You will need to submit a letter of employment, though, and an Option C printout to show that you are not in receipt of social assistance. No minimum income requirement means they can't refuse you as a sponsor because you don't meet income levels, but they still want to know that you can support the person you're sponsoring, and if you can't, they will sometimes refuse the application saying that the applicant has not convinced them that they are willing/able to support themselves.