What does this capital gains tax calculator estimate?
This calculator estimates the arithmetic result for one stock disposition: net sale proceeds minus the adjusted cost basis of the shares sold. A positive result is a modeled gain; a negative result is a modeled loss. The optional rate is applied only to positive gain to show a hypothetical amount. No rate is selected for you, and the result is not an estimate of your full federal, state, or local tax bill.
The IRS explains that gain or loss generally comes from subtracting adjusted basis from the amount realized on a sale or trade. For stock bought for cash, basis generally starts with purchase price and may include purchase costs. Basis can change after stock splits or certain distributions. Inputs should reflect the actual shares and transaction rather than a guessed average.
Share identification and holding period can affect reporting. Investors may have lots bought at different prices and dates. This tool does not select lots, establish basis, classify a gain as short-term or long-term, handle wash-sale adjustments, combine sales, or calculate loss carryovers. It also excludes dividends, options, employee compensation, inherited or gifted shares, and other special situations.
The assumed rate is user supplied. Tax outcomes can depend on holding period, filing status, taxable income, other gains and losses, deductions, and additional taxes. One percentage on one positive gain cannot reproduce those rules or a Schedule D calculation. A displayed zero for a modeled loss does not mean the loss has no tax significance; loss deductibility and netting are outside this calculator.
Use transaction records to identify shares sold and adjusted basis. Review current IRS instructions or seek qualified tax help when reporting a transaction. This page is educational information rather than tax or investment advice.
Frequently asked questions
How is the modeled gain calculated?
Subtract the adjusted basis of the shares sold from net sale proceeds. The calculation does not verify either input or account for other transactions.
Does this calculate my short-term or long-term rate?
No. It does not determine holding period or choose a rate. Entering a rate only shows a hypothetical multiplication on positive modeled gain.
Does a modeled loss mean I can deduct the full amount?
No. Loss netting, deduction limits, carryovers, and other restrictions are not modeled. See current IRS guidance for your situation.
Where can I check stock basis and sale rules?
Review IRS Publication 550 and the current Schedule D instructions, and keep records supporting the shares and basis reported.