An exchange or account is no longer available
Historical trades, deposits, or withdrawals are missing because a provider closed, an account was lost, or exports cover only part of the holding period.
Cost basis reconstruction
Reconstruct missing crypto cost basis without turning gaps into guesses.
When assets move between old exchanges, self-custodied wallets, brokers, and tax software, acquisition history can break long before a disposition appears on a report. We rebuild the supported record, preserve uncertainty, and prepare a clear handoff for tax and accounting review.
Discuss your needsWhen to call
A practical fit for moments when the records must support a decision.
Assets moved through self-custody
A broker or tax report sees the disposition but not the earlier acquisition or the transfers connecting the original source to the final account.
Software shows zero or unknown basis
Imports contain negative balances, unidentified deposits, duplicate transactions, or default values that are not supported by the underlying records.
Potential deliverables
A scope built around usable work products.
Depending on the available records, stakeholders, and agreed level of review, an engagement may include:
- Inventory of affected assets, wallets, accounts, providers, periods, and available source records
- Acquisition-history schedule with evidence references for supported dates, quantities, costs, and transaction costs
- Transfer-matching schedule connecting supported movement between accounts under common ownership
- Wallet- and account-level lot schedule for the agreed assets and periods
- Exceptions register separating missing records, unsupported amounts, fact questions, and professional judgments
- Documented handoff package for the taxpayer, accountant, and engaged tax professional
How we help
A disciplined approach to digital asset complexity.
Evidence recovery
Inventory original exports, confirmations, fiat records, wallet history, prior reports, and other evidence that can support acquisition facts.
Wallet- and account-level reconstruction
Rebuild supported acquisition lots, connect same-owner transfers, and reconcile quantities without pooling unexplained balances.
Transparent exceptions
Separate verified basis, fact-dependent items, assumptions, and unresolved gaps so the final reviewer can see what the records do and do not establish.
Engagement process
From source records to a documented operating path.
Define the affected population
Confirm the taxpayer or entity, assets, wallets and accounts, periods, dispositions, deadlines, and reports that depend on the missing basis.
Preserve and recover evidence
Collect original exports and statements, wallet and transaction records, fiat support, prior reports, and third-party records without overwriting the source history.
Reconstruct and reconcile
Build supported acquisition lots, connect transfers, reconcile quantities, and investigate differences at the wallet and account level.
Document what remains open
Deliver the agreed schedules with evidence references, assumptions, limitations, and unresolved items for final professional review.
Common questions
Define the scope before the work begins.
Can blockchain data alone establish cost basis?
Usually not. Blockchain records can support asset identity, addresses, quantities, and on-chain movement, but they generally do not establish who owned an address, the fiat or off-chain consideration paid, the purpose of a transaction, or every transaction cost. Reconstruction normally requires both on-chain and off-chain records.
Does missing cost basis mean the basis is zero?
Not necessarily. A blank broker or software field does not by itself prove zero basis, but special rules can require a zero-basis reporting result when required substantiation is unavailable. The appropriate treatment depends on the facts and should be determined with the engaged tax professional.
Can every missing lot be reconstructed?
No. The result depends on the evidence available. Bit Bookkeeper can rebuild supported history and document reasonable connections, but it will not invent acquisition dates, prices, ownership, or transaction purpose merely to make a report calculate.
How is this different from broad transaction cleanup?
Transaction cleanup repairs the wider source population, balances, duplicates, classifications, and transfer breaks. Cost basis reconstruction is a narrower workstream focused on acquisition history and lot support for specified assets and dispositions. A cleanup engagement may identify basis gaps that require a separate reconstruction scope.
How is this different from 1099-DA reconciliation?
Cost basis reconstruction focuses on recovering acquisition history across the full wallet and account chain. Form 1099-DA reconciliation focuses on comparing a particular broker form with source records and documenting discrepancies. An engagement may require one or both workstreams.
Engagement outcomes
Clarity you can act on.
Every engagement is scoped around the available facts, required level of review, and the decisions your organization needs to support.
Supported acquisition-history schedule
Wallet and account transfer map
Basis evidence and exceptions register
Tax-professional review package
Begin the conversation
Digital assets deserve professional accounting.
Tell us where the complexity sits. We’ll help define a practical next step.
Request a consultation