There are many reasons you might need to know the fair market value of an asset: you plan to sell it or buy it, you want to donate the item to charity or give it to a family member, you need to insure against loss or the property is part of an estate division. Some assets may be easy to value. Publicly traded stock, for example, is generally valued at the mean (average) between the high and low selling prices for the date of the transfer.
Sometimes you’ll need a qualified appraisal for tax purposes: to claim a charitable deduction for noncash gifts (except publicly traded stock) to charity in excess of $5,000 ($10,000 if the gift is closely held stock), to prove the value of assets given to family members that exceed the $15,000 annual exclusion or to determine the value of an estate’s assets.
It’s important to engage someone who is knowledgeable in the field that is being appraised. This is especially true if you think the IRS may challenge the value placed on the property.