Tax deduction is a reduction of the income subject to tax, for various items, especially expenses incurred to produce income. Often these deductions are subject to limitations or conditions.
Basically, what this means is if you have spent money to pay for things to do with your job. E.g. uniforms, union fees, RSA/RCG, work related courses, safety equipment (safety boots, high visibility vest, etc), stationary, tools, travel between jobs and work sites, uniform and laundry receipt. Items & services like this are all tax deductible. You could get a large percentage of this money back in your tax refund.
