Basis is a common IRS term, but probably does not enter into your everyday conversation. This IRS term is important because it impacts the taxes you pay when you sell, exchange or give away property.
What basis is
The IRS describes basis as:
The amount of your capital investment in a property for tax purposes. Use your basis to figure depreciation, amortization, depletion, casualty losses, and any gain or loss on the sale, exchange or other disposition of the property.
In plain language, basis is the cost of your property as defined by the tax code.
There are a few different types of basis that apply to different situations, including "cost basis," "adjusted basis," and "basis other than cost."