The first two articles in this series covered the rate impact (California adds 9-13% to Bitcoin gains on top of federal) and the residency rules (you can move out, but the FTB will scrutinize). This article goes one level deeper: the actual filing mechanics for California Bitcoin holders. Cost basis methods, lot identification, and the timing gotchas that catch even well-organized filers.
California conforms to federal cost basis rules — mostly
California uses the same cost basis as federal for capital gains calculations. If you bought Bitcoin for $30,000 and sold it for $80,000, your gain is $50,000 on both your federal Schedule D and your California Schedule D-1. That much is straightforward.
Where it gets more nuanced: California has its own conformity rules and does not always automatically pick up federal changes. If Congress changes a basis rule mid-year, California may take months or years to adopt the change, and in some cases never adopts it. As of 2025, the federal-to-California conformity for Bitcoin cost basis is essentially in alignment, but you should check the FTB conformity table annually if you are doing significant Bitcoin tax planning.
Lot identification: FIFO, specific identification, and average cost
If you bought Bitcoin in multiple tranches at different prices, the IRS allows three lot identification methods (Notice 2014-21 followed by subsequent guidance):
- FIFO (first-in, first-out): the default. The earliest-purchased coins are sold first. Generally produces the largest gain in a rising market.
- Specific identification: you choose which lots to sell, recorded at the time of sale. Requires you to identify the specific coins (by acquisition date and cost basis) before or contemporaneous with the sale, with adequate records to substantiate.
- Average cost: not currently allowed for cryptocurrency at the federal level. (It is allowed for mutual funds in some cases, but not for digital assets.)
California follows the federal rules here. Specific identification is the highest-leverage tax planning tool you have as a Bitcoin holder — it lets you choose which lots to harvest, balancing gains and losses across different cost bases. But the substantiation requirement is strict.
What “adequate records” actually means
For specific identification to hold up under FTB or IRS audit, you need contemporaneous records showing:
- The exact lot identifier (transaction hash, exchange transaction ID, or wallet UTXO reference)
- The acquisition date and time
- The acquisition cost basis (in USD at the time of purchase)
- The disposal date and time
- The disposal proceeds
- The FIFO/specific-identification election made at or before the sale, not retroactively
The “at or before the sale” requirement is where most amateur filers get caught. Going back at year-end and “selecting” the highest-basis lots after the fact does not qualify as specific identification. The decision must be documented contemporaneously — ideally before you place the sell order.
Practical solution: tools like CoinTracker, Koinly, or TaxBit can record specific identification elections at the moment of sale and produce audit-defensible documentation. If you are running specific identification by hand, you need a contemporaneous note (timestamp, lot reference, sale order ID) every time.
Wash sale rules do not apply to Bitcoin (yet)
Wash sale rules under IRC § 1091 prohibit claiming a loss on a security if you repurchase a substantially identical security within 30 days. As of 2025, those rules only apply to “stocks and securities,” and the IRS has not classified Bitcoin as either. Bitcoin is currently not subject to the wash sale rule at the federal or California level.
This is a significant tax planning opportunity. You can sell a losing lot, immediately repurchase, and book the loss to offset gains elsewhere. Federal proposals to extend wash sale rules to digital assets have been floated but not enacted. Watch this space — the rule could change in any tax year.
Like-kind exchange does not apply to Bitcoin
Pre-2018, some practitioners argued Bitcoin-to-Bitcoin or Bitcoin-to-other-crypto trades qualified for IRC § 1031 like-kind exchange treatment, deferring the gain. The Tax Cuts and Jobs Act eliminated this for all property except real estate, effective 2018. Every crypto-to-crypto trade is a taxable disposition at federal and California levels. There is no wiggle room here.
Reporting forms and where everything goes
- Federal: Form 8949 (transaction-level detail), Schedule D (summary), then onto Form 1040. Long-term and short-term transactions separated.
- California: Schedule D-1 for the gain/loss summary, Form 540 (resident) or 540NR (part-year/nonresident).
- Bitcoin question on Form 1040: as of recent tax years, the IRS asks a yes/no question about digital asset transactions on Form 1040. Answer “yes” if you bought, sold, traded, or received any digital asset during the year.
Five timing gotchas for California filers
- December trades that settle in January. Sale date for tax purposes is the trade date, not the settlement date. A December 30 sale is a current-year transaction even if proceeds settle on January 2.
- Estimated tax payments. California requires estimated payments if you expect to owe more than $500 in state tax. A large Bitcoin gain triggers underpayment penalties if you do not bump up your Q4 estimate the year of the sale.
- The “constructive receipt” trap on rewards. Bitcoin received as staking rewards, mining rewards, or income is taxed as ordinary income at fair market value on the date of receipt, not when you eventually sell. Both federal and California treat this consistently.
- Hard forks and airdrops. Treated as ordinary income at FMV on the date you have control. Easily missed. Both federal and California.
- Charitable contributions of Bitcoin. If held over one year, you can donate appreciated Bitcoin to a 501(c)(3) and deduct the FMV without realizing the gain. Significant California tax savings opportunity for high-bracket holders. Requires a qualified appraisal for donations over $5,000.
When you should file an FTB Form 540 vs 540NR
- Form 540: California resident for the entire tax year. Most CA-based Bitcoin holders.
- Form 540NR: Part-year resident (you moved in or out of California during the year) or non-resident with California-source income.
If you moved out of California mid-year and sold Bitcoin after the move (Article 2 territory), you file 540NR for that year and report only the pre-move gains plus any California-source income. The Bitcoin sale itself, if executed cleanly post-move, is generally not California-source income. The “executed cleanly” caveat is doing a lot of work in that sentence — see Part 2 for the residency mechanics.
Bottom line
California conforms to federal cost basis rules but adds its own progressive rate on top. Specific identification of lots is the highest-leverage planning tool, but the substantiation requirement is strict and contemporaneous. Wash sale rules do not yet apply to Bitcoin (track this; the rule could change). Like-kind exchange does not apply at all. Reporting flows through Form 8949 / Schedule D / Schedule D-1. The compliance lift is manageable with a tracking tool and a CPA who has actually filed Bitcoin returns before. Do not improvise.