Adjusted Cost Basis is the total amount you've invested in an asset, adjusted for various additions and deductions over its holding period. It starts with your original purchase price and is modified by factors like reinvested dividends, stock splits, return of capital distributions, and improvement costs. When you eventually sell the investment, the difference between your sale price and adjusted cost basis determines your capital gain or loss for tax purposes.
How It Works
Your adjusted cost basis begins at the price you pay to acquire an investment. From there, you add costs that increase your basis—such as brokerage commissions, investment fees, or capital improvements. You subtract amounts that reduce your basis, including return of capital distributions and depreciation deductions. For equity investments, stock splits and stock dividends can also affect your basis per share. If you reinvest dividends, those amounts increase your basis since you're effectively buying additional shares at their fair market value.
Why It Matters for Investors
Adjusted cost basis directly impacts your tax liability. A higher basis reduces your taxable capital gains; a lower basis increases them. As an angel investor or entrepreneur managing a portfolio, accurate basis tracking is essential for tax planning and compliance. It also gives you a clearer picture of your true investment performance, separate from tax considerations. High-net-worth investors often use basis information strategically when deciding which securities to sell, a practice known as tax-loss harvesting. Additionally, your executor will use the adjusted cost basis of your assets at death to calculate the step-up in basis for heirs.
Example
Suppose you purchase 100 shares of a startup at $10 per share, spending $1,000 total. You pay $50 in brokerage commissions, bringing your adjusted cost basis to $1,050. The company later issues a 2-for-1 stock split, giving you 200 shares but lowering your per-share basis to $5.25. Two years later, the company declares a $0.50 per-share dividend that you reinvest, purchasing 20 additional shares at $15 each ($300 total). Your new adjusted cost basis is now $1,350 spread across 220 shares, or $6.14 per share. When you eventually sell, this $1,350 figure determines your gain or loss.
Key Takeaways
- Adjusted cost basis equals your purchase price plus additions and minus subtractions over the holding period
- Accurate basis tracking is critical for calculating capital gains taxes and investment performance
- Common adjustments include reinvested dividends, stock splits, commissions, and return of capital distributions
- Higher basis means lower taxable gains; strategic basis management supports effective tax planning