to make an IRA contribution of $8K you'll need $8k of compensation. if compensation is less that's the limit.
compensation includes:
wages (box 1)
net income from self-employment after deducting 1/2 the SE tax
certain taxable alimony income
you should be able to go through Turbotax and enter the $8k. Then Turbotax will tell you if it's deductible or in excess.