Company bitcoin gain calculator: UK and US worked examples

Sources checked 9 November 2026. These are worked examples, not a tax return and not tax advice. They show how the published rules turn a list of purchases and sales into a gain or loss, using the figures you enter. Your accountant should confirm how the rules apply to your company. If anything here conflicts with the linked source, the source wins.

UK: how a company's gain is worked out

A UK company that holds bitcoin as an investment, rather than as part of a trade, is generally charged Corporation Tax on chargeable gains when it disposes of it. Selling for pounds, swapping for another token, spending it and giving it away can all be disposals.

Source: HMRC: CRYPTO41200: Corporation Tax on chargeable gains, introduction, HMRC: CRYPTO41050: Corporation Tax on cryptoassets for businesses, introduction.

Matching order. Bitcoin bought by a company goes into one pool per token type, with one pooled cost (the "section 104 pool"). HMRC describes two exceptions for companies, which are applied first:

1. Same day. A disposal is matched with bitcoin bought on the same day, even if the sale happened first.
2. Ten days. Where the company buys and then disposes of bitcoin within ten days, the disposal is matched with the purchases in the previous nine days, earliest first.
3. The pool. Anything left is taken from the pool at average cost: pooled cost multiplied by the share of the pool sold.

Source: HMRC: CRYPTO41350: Corporation Tax on chargeable gains, pooling (with the same-day and ten-day exceptions for companies), legislation.gov.uk: Taxation of Chargeable Gains Act 1992, section 104: share pooling, including other fungible assets, legislation.gov.uk: Taxation of Chargeable Gains Act 1992, section 107: identification of securities for companies (same day and ten days).

Check the ten-day boundary with your adviser. HMRC's manual describes the window as purchases "within the previous nine days"; section 107 of the Act refers to a period of ten days. The calculator matches a sale with purchases one to nine days earlier and treats older purchases as pooled. If your company has purchases and sales close to that boundary, ask your adviser to confirm the match.

Costs. The allowable cost includes the price paid and incidental costs such as exchange fees on the purchase; fees on the sale reduce the proceeds. HMRC lists which costs are and are not allowable.

Source: HMRC: CRYPTO41300: Corporation Tax on chargeable gains, allowable costs, legislation.gov.uk: Taxation of Chargeable Gains Act 1992, section 38: acquisition and disposal costs.

Sterling values. Each transaction is converted to sterling at the time it happens, using a reasonable method applied consistently and recorded.

Source: HMRC: CRYPTO40100: Cryptoassets for businesses, valuation (converting to sterling).

Rate. For profits from 1 April 2023, the main rate of Corporation Tax is 25% (profits over 250,000 pounds) and the small profits rate is 19% (profits of 50,000 pounds or less), with marginal relief between the two. The limits are reduced for short accounting periods and for associated companies. The calculator applies one rate you choose to the gain alone, so the tax figure is only an illustration.

Source: GOV.UK: Corporation Tax rates and allowances.

Losses. An allowable loss can generally be set against the company's chargeable gains, and HMRC notes it must be reported.

Source: HMRC: CRYPTO41400: Corporation Tax on chargeable gains, losses.

Check it against HMRC. Press HMRC's M Ltd example. It loads the figures from HMRC's own example in CRYPTO41350: a pool of 14,000 tokens costing 200,000 pounds, a purchase of 500 for 17,500 pounds, and a sale of 4,000 for 160,000 pounds five days later. The calculator gives the same answer as HMRC: a gain of 2,500 pounds on the 500 matched under the ten-day rule, a gain of 90,000 pounds on the 3,500 from the pool, and a pool of 10,500 tokens costing 150,000 pounds afterwards.

US: how a C corporation's gain is worked out

For US federal tax, bitcoin is property. A C corporation that sells it, swaps it or spends it has a gain or loss: the amount realized minus the adjusted basis of the units treated as sold.

Source: IRS: Notice 2014-21: virtual currency is treated as property (PDF), IRS: Digital assets.

Basis and fees. The basis of bitcoin bought for cash is the cash paid plus the transaction costs allocable to the purchase. Costs of a sale are allocated to the sale and reduce the amount realized: a 10 dollar sale with a 1 dollar fee realizes 9 dollars.

Source: eCFR: 26 CFR 1.1012-1(h) and (j): basis of digital assets and which units are treated as sold (applies from 1 January 2025), eCFR: 26 CFR 1.1001-7(b)(2): digital asset transaction costs reduce the amount realised.

Which units are sold. From 1 January 2025, units are identified wallet by wallet (or account by account):

• Not held with a broker (for example a company multisig wallet): units are treated as sold first in, first out within that wallet, unless the company specifically identifies the units in its books and records by the date and time of the sale.
• Held with a broker: first in, first out within that account, unless the company gives the broker an adequate identification by the time of the sale. A standing order counts. For 2025 and 2026, IRS notices allow some identifications to be made in the company's own books and records instead.
• Moving from older methods: Revenue Procedure 2024-28 sets out how unused basis was allocated to each wallet or account at the start of 2025.

Source: eCFR: 26 CFR 1.1012-1(h) and (j): basis of digital assets and which units are treated as sold (applies from 1 January 2025), IRS: Notice 2025-7: temporary relief for identifying units held with a broker (PDF), IRS: Notice 2026-20: extends the Notice 2025-7 relief to 31 December 2026 (PDF), IRS: Revenue Procedure 2024-28: allocating unused basis to wallets and accounts (PDF).

Holding period and rate. Bitcoin held more than one year gives a long-term gain or loss; otherwise it is short term. A C corporation pays the same 21% federal rate on both, so the split mainly matters for records and losses.

Source: Cornell LII (unofficial copy of the US Code): 26 U.S.C. 1222: short term and long term (held more than 1 year), Cornell LII (unofficial copy of the US Code): 26 U.S.C. 11(b): corporate income tax at 21 percent.

Losses. A corporation can deduct capital losses only against capital gains. A net capital loss is generally carried back three years and forward five years, as a short-term loss.

Source: Cornell LII (unofficial copy of the US Code): 26 U.S.C. 1211(a): corporate capital losses allowed only against capital gains, Cornell LII (unofficial copy of the US Code): 26 U.S.C. 1212(a): corporate capital loss carryback (3 years) and carryover (5 years).

Check it against the regulation. Press Facts from the regulation's examples. It loads the lots used in Examples 1 and 2 of Treas. Reg. 1.1012-1(j)(5): 10 units bought at 2 dollars each, 20 units bought a year later at 5 dollars each, and 10 units sold at 10 dollars each. With first in, first out, the 10 oldest units are sold (basis 20 dollars, gain 80 dollars, long term). With specific identification of the newer units, the basis is 50 dollars and the gain 50 dollars, short term. The dates are illustrative; the regulation uses "Year 1" and "Year 2".

What these calculators do not cover

The examples are deliberately narrow. They do not cover:

• UK: companies that trade in bitcoin or hold it as trading stock; bitcoin within the intangible fixed assets rules (HMRC explains when that regime takes priority); indexation allowance on bitcoin held before 1 January 2018 (frozen for companies at December 2017); a functional currency other than sterling; marginal relief, associated companies and short accounting periods; connected party transactions; group relief and loss restrictions; negligible value claims, lost keys and theft.
• US: S corporations, partnerships and LLCs taxed as partnerships (gains pass through to owners); dealers and traders; several wallets or accounts at once; the transition under Revenue Procedure 2024-28; state and local tax; the corporate alternative minimum tax; book and tax differences under ASU 2023-08; Form 1099-DA reconciliation.
• Both: mining, staking and airdrop income; swaps for other tokens and paying fees in bitcoin; gifts and payments to staff or suppliers; anything other than bitcoin.

Source: HMRC: CRYPTO41150: Corporation Tax, intangible fixed assets, HMRC: CG17200: Capital Gains Manual, indexation allowance (frozen for companies from 1 January 2018).

If any of these apply, the calculator's result is not a reliable guide. Take the full facts to your accountant.

Read next

• Company bitcoin tax, UK and US, for the wider HMRC and IRS rules.
• Accountant's corner, for recording bitcoin and year end evidence.
• Bookkeeping examples and workbook, for the records these calculations need.
• Policy health check, to check your draft policy covers tax records.

Sources

Primary sources only. Each link was checked on 9 November 2026. Rules change, so confirm the current version with your adviser.

1. HMRCCRYPTO41200: Corporation Tax on chargeable gains, introduction
2. HMRCCRYPTO41050: Corporation Tax on cryptoassets for businesses, introduction
3. HMRCCRYPTO41350: Corporation Tax on chargeable gains, pooling (with the same-day and ten-day exceptions for companies)
4. legislation.gov.ukTaxation of Chargeable Gains Act 1992, section 104: share pooling, including other fungible assets
5. legislation.gov.ukTaxation of Chargeable Gains Act 1992, section 107: identification of securities for companies (same day and ten days)
6. HMRCCRYPTO41300: Corporation Tax on chargeable gains, allowable costs
7. legislation.gov.ukTaxation of Chargeable Gains Act 1992, section 38: acquisition and disposal costs
8. HMRCCRYPTO40100: Cryptoassets for businesses, valuation (converting to sterling)
9. GOV.UKCorporation Tax rates and allowances
10. HMRCCRYPTO41400: Corporation Tax on chargeable gains, losses
11. IRSNotice 2014-21: virtual currency is treated as property (PDF)
12. IRSDigital assets
13. eCFR26 CFR 1.1012-1(h) and (j): basis of digital assets and which units are treated as sold (applies from 1 January 2025)
14. eCFR26 CFR 1.1001-7(b)(2): digital asset transaction costs reduce the amount realised
15. IRSNotice 2025-7: temporary relief for identifying units held with a broker (PDF)
16. IRSNotice 2026-20: extends the Notice 2025-7 relief to 31 December 2026 (PDF)
17. IRSRevenue Procedure 2024-28: allocating unused basis to wallets and accounts (PDF)
18. Cornell LII (unofficial copy of the US Code)26 U.S.C. 1222: short term and long term (held more than 1 year)
19. Cornell LII (unofficial copy of the US Code)26 U.S.C. 11(b): corporate income tax at 21 percent
20. Cornell LII (unofficial copy of the US Code)26 U.S.C. 1211(a): corporate capital losses allowed only against capital gains
21. Cornell LII (unofficial copy of the US Code)26 U.S.C. 1212(a): corporate capital loss carryback (3 years) and carryover (5 years)
22. HMRCCRYPTO41150: Corporation Tax, intangible fixed assets
23. HMRCCG17200: Capital Gains Manual, indexation allowance (frozen for companies from 1 January 2018)