Cost Basis Definition and Meaning

What you originally paid for an asset (including fees), adjusted for splits and dividends. It's the starting point for calculating your gain or loss when you sell.

Your cost basis is basically the answer to "what did I pay for this?" When you sell an investment, the IRS calculates your taxable gain (or loss) as the sale price minus your cost basis. Simple concept, but the details get tricky fast.

The basics: your cost basis starts with the purchase price plus any commissions or fees. But things like stock splits, reinvested dividends, corporate actions, and gifts or inheritance can all adjust that number. If you've been buying the same stock in small chunks over the years, each purchase creates its own "tax lot" with its own basis.

Brokerages are required to report cost basis to the IRS for stocks purchased after 2011, mutual funds after 2012, and other securities after 2014. For crypto, exchanges are just starting to report basis—and many older transactions have no broker-reported basis at all.

Your choice of cost basis method matters more than you might think. FIFO (first in, first out), LIFO (last in, first out), specific identification, and average cost can all produce very different tax results for the same sale. FIFO tends to work well for long-term holders, while specific identification gives active traders the most control over their tax bill.

If you hold assets across multiple platforms, keeping your cost basis accurate means consolidating data from everywhere. Moving crypto between wallets or transferring shares between brokers doesn't change your basis—but the receiving platform often won't have your original purchase info, which makes tracking harder.

Frequently Asked Questions

▸What happens to cost basis when you transfer crypto between wallets?

Your cost basis stays the same—transferring between your own wallets isn't a taxable event. The catch is that the receiving wallet probably won't know what you originally paid, which is why a tracking tool that follows transfers is so helpful.

▸How is cost basis calculated for gifted assets?

You generally inherit the giver's cost basis (called carryover basis). However, if the asset was worth less than the giver's basis at the time of the gift, special rules kick in for calculating a loss.