Tax
Cost basis is what an asset really cost you — the price plus the commissions, charges and improvements that attach to it.
What you paid for the asset
Base price paid for the asset, in your local currency.
Costs that add to the basis
Brokerage or agent commissions on the purchase.
Stamp duty, legal, registration, or transfer charges.
Capital improvements that add to the asset’s value.
Cost Basis
10,650
Purchase price plus all added costs.
Formula verified 12 September 2026
Total Costs Added
650.00
Commissions, charges, and improvements combined.
Educational estimate only — verify rates with your official tax authority. Read the full disclaimer ↓
Each cost that stacks on top of the bare purchase price to form the cost basis, from the values you entered, with each item shown as a share of the total. A bigger basis means a smaller taxable gain when you sell.
| Component | Amount | Share of basis |
|---|---|---|
| Purchase price | 10,000 | 93.9% |
| Commissions | 100 | 0.9% |
| Other charges | 50 | 0.5% |
| Improvements | 500 | 4.7% |
| Cost basis | 10,650 | 100% |
Estimates only — not financial, tax, or professional advice.
100% private — every number you enter is calculated in your browser and never sent to our servers.
What it calculates: Cost Basis, Total Costs Added.
Updated 5 June 2026 · Transparent assumptions
Gain is proceeds minus basis, so basis reduces the taxable amount one for one. People routinely enter only the purchase price, forget the brokerage, the stamp duty and the legal fees, and pay tax on money they never made.
The discipline this calculator enforces is simply listing the components separately, which is also the form a tax authority wants to see them in if the figure is ever queried.
Costs of acquiring the asset generally add to basis: brokerage, stamp duty, registration, legal and survey fees. So do capital improvements — work that adds to the asset or extends its life, such as an extension or a new roof.
Routine maintenance does not. Repainting, fixing a leak and annual servicing are expenses of ownership, not additions to what the asset cost. The line between a repair and an improvement is where most disputes occur, and it is worth documenting which side a large spend falls on at the time.
On an asset that has been depreciated for tax — a rental property, business equipment — the depreciation claimed reduces the basis, which raises the gain on sale. This calculator does not deduct depreciation, so anyone who has claimed it must subtract it from the figure produced here.
Share basis also moves with corporate actions. A stock split multiplies the units and divides the per-unit basis, a bonus issue spreads the same basis across more shares, and a return of capital reduces it. The total basis is what survives; the per-unit figure is not.
Claiming an improvement you cannot evidence is the most common way a basis figure fails under scrutiny. Contractor invoices, bank records and completion certificates are what make a number defensible years later, when the asset is sold and the work is a distant memory.
This matters most for assets held for decades, which is exactly when improvements accumulate and receipts disappear. Keeping a running file from the start costs nothing and is worth considerably more than the reconstruction attempt that otherwise replaces it.
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
Tax disclaimer
Tax rules vary by country, state, tax year, filing status, income type, deductions, and exemptions. This calculator is educational and uses the values you enter. Always verify final tax treatment with official sources or a qualified tax professional.
How we calculate · Found an error? email us
Published 12 September 2026