Question

fill in the blank question all sources of income are taxable unless specifically excluded through a tax provision. however, \boxed{} are not permitted unless a specific tax provision allows them.

Explanation:

The sentence is about tax rules. The first part says income is taxable unless excluded by a tax provision. The second part, with the blank, should contrast: deductions (or similar tax - related exclusions/allowances) are not permitted unless a specific tax provision allows them. In tax law, deductions (or "deductions", "exclusions" could also work, but "deductions" is common here) follow the rule that they aren't allowed unless a tax provision permits. So the most appropriate word to fill in the blank is "deductions" (or "exclusions", but "deductions" is more typical in this context).

Answer:

deductions