Average Cost Basis

Average cost basis is a method of calculating the cost of an investment for tax purposes by dividing the total amount paid across all purchases by the total units held. An investor who bought 1 bitcoin at 40,000 dollars and 1 at 60,000 has an average cost basis of 50,000 dollars per coin.

Why it matters

The basis method chosen determines the size of the taxable gain on every sale. Average cost is the common default for mutual funds because it is simple, but it surrenders control: selling specific high-cost lots to minimize gains, known as specific identification, usually produces a better tax outcome. In the United States, average cost is generally not a permitted method for property such as crypto and precious metals, where taxpayers instead use specific identification or first in, first out.

US broker reporting rules effective in 2025 also require crypto basis tracking on a per-account basis, making clean records more important than ever.

In the gold vs bitcoin debate

Basis tracking is where dollar-cost averaging into either asset meets the tax code. A stack of gold coins bought over 20 years and a bitcoin balance accumulated through hundreds of small purchases pose the same problem: every unit has its own purchase price and date. Bitcoin holders have an edge in tooling, since exchanges and portfolio software log each lot automatically, while coin buyers must keep receipts by hand. In both cases the record keeping, not the math, is the hard part.