Applications · Onchain
A crypto tax figure you can defend.
Wallets, exchanges, and DeFi positions leave history in pieces. A tool stitches them together and returns one number — and when the tax office or an auditor asks why that number and not another, nobody can reproduce it. A borrow read as income inflates the gain. A holding whose acquisition was never read has no cost, so the whole disposal is taxed. The bill for that is an amended return with back taxes and penalty interest, and weeks of an accountant’s time reconstructing by hand what the tool would not explain.
Ethereum, Base, Arbitrum, and Optimism, merged with exchange statements. Realised gain, holdings, and the year-end mark come back with the method behind them, the source of every valuation, and an explicit list of what a person still has to decide.
Derived, not asserted
History is read from the wallet's first transaction, so cost basis comes from acquisitions that actually happened rather than an opening balance typed in by hand. 移動平均法 or 総平均法 is elected and recorded alongside the figure, and the arithmetic stays exact — a gain recomputed years later agrees with itself.
Every yen carries its source
A swap prices itself: what left is valued by what arrived, once, on chain, forever. Pegged assets go through a published FX rate; an external price feed is the last resort and names its source and moment. Anything nothing could price is surfaced, never guessed.
Agent transfers keep their reason
The chain records that assets moved and nothing about why. Gateway attestations carry the declared purpose and approval status recorded at the time, and the commitment opening is verified against the transaction hash — proving which transfer it was without publishing every counterparty.
Corporate year-end and the wallet set
Holdings with an active market are marked at period close under 実務対応報告第38号 and reported apart from realised gain, so neither figure contaminates the other. Addresses that trade in both directions with yours are ranked as candidates — a forgotten wallet is what overstates a gain.
Why This
Other tools compute the number. We hand over the case for it.
Filing software is built to produce a figure quickly. Nothing in that job requires the figure to survive a question — and the question is what an audit consists of.
Classification — typical tool
An address heuristic decides whether a transfer was income, a loan, or your own withdrawal — silently, with no record that a choice was made at all.
Classification — Noah's Ark
A transfer an agent made carries the reason recorded at the time. Everything else is a stated decision per counterparty, written in the method file, visible to whoever checks the return.
Valuation — typical tool
One price feed values everything, including swaps the chain already priced. Rerun it next year against a revised feed and the same trades give a different gain.
Valuation — Noah's Ark
A swap is valued once, by its own counter-asset. Every figure is graded by how much had to be trusted, and the report states how much of the total the trades themselves priced.
Reproducibility — typical tool
A CSV of results. The basis method, the wallet set, and the judgments behind them live inside the product, so the working cannot be re-derived without it.
Reproducibility — Noah's Ark
The method version, basis method, wallet set, and each open judgment ship next to the figure. Exact rational arithmetic means a recomputation years later agrees to the yen.
Corporate close — typical tool
Built for an individual filing. The period-end mark corporations owe is bolted on, if it appears at all, and lands mixed into realised gain.
Corporate close — Noah's Ark
実務対応報告第38号 marks are computed only when asked for and reported on their own line, because an unrealised movement belongs on neither the realised figure nor a person’s return.
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