Income deduction refers to the amount of money that taken from your income to be allocated into other payments. The amount that being taken should be transparent, being done on timely basis, and intentional.
Example of income deduction include things such as: retirement savings, income tax, medicare, etc.
An example of an income deduction is "retirement savings."
When you are working on declaring and paying your taxes, an income deduction is the expenses that can be deducted. The income has to be considered to calculate the taxes you need to pay annually. If we are talking about retirement savings, these have tax benefits that vary according to your retirement plan.