How to exclude collected GST amount from Gross Income on T4A

The Self Employed Commission amount reported (from real estate salesperson commission) on my T4A slip includes the amount of GST collected on the commission. So;

If , for example, the Commission amount reported is 10,000 and of that there was 1,300 in GST collected then my net income (not considering all the other aspects) should be reported as 8,700.....correct? (since I've already remitted the 1,300 as part of my GST filing)

 

How do I claim that 1,300 on my income tax return in order to reduce my taxable income amount?

Thanks!