Q: does someone have to pay taxes on intrest earned on a cd if he doesnt file a tax return since hes unemployed
A: If the amount of the interest is above the minimum amount of income required to trigger the necessity of filing an income tax return, then the answer is yes.
In other words, if the amount of interest (for example) is $1000 and that is taxable income, then you must file a return and pay taxes on that amount.
The amount of this interest, if it is above a certain amount, will be reported to the taxing authorities who will be waiting in the lobby of their building for your return. Do not disappoint them.