Do I Have To Pay Capital Gains Taxes On Money I Lost In Mutual Funds?

Normally speaking, any investment is only taxable when it is liquidated, i.e. Cashed out.  Tax is charged on the basis of the profit, i.e. The increase in the value of the money you receive over the value of the money originally invested.  Should the amount you receive be less than you paid in, then you should receive a tax refund calculated at the same rate as the tax you would have paid if you had made a profit, currently 15% in the USA.  So each $100.00 of profit will mean you must pay out $15.00 in tax.  Each $100.00 of loss will mean you should receive a $15.00 refund.  But only if you have cashed out your investment during the tax year in question.