BOB stands for Build on Bitcoin, but the network settles to Ethereum rather than to Bitcoin, and gas is paid in ETH rather than in BTC.
That surprises people who arrive expecting to pay fees in bitcoin. You need ETH here, the same as on any other Ethereum layer 2.
Its Bitcoin connection is real but narrower than the branding suggests: contracts on BOB can check that a Bitcoin transaction happened, and bitcoin can be brought over by a service that swaps it for you.
What you get out of the box
Pick your import method.
On BOB
- Open your wallet and copy your address. It starts with 0x and matches your Ethereum address.
- If you brought bitcoin over, add your Bitcoin wallet too. That side of the trade is not visible here.
On Kryptos
- Go to Kryptos.io and sign up with your Google account.
- From the menu, click Integrations.
- Click Add Integration and search for BOB.
- Click the BOB icon, then choose Import using Address.
- Give the wallet a name, paste your address, and click Import Your Transactions.
Good to know
- Gas is paid in ETH, not BTC, despite the name.
- Bringing bitcoin over means somebody swaps you a wrapped version of it. Which wrapper you get depends on the route.
- The airdrop claim window closed on 4 January 2026 and unclaimed tokens were forfeited.
What BOB is, underneath the branding
Bitcoin layer 2 is a marketing phrase covering at least four different arrangements, and the differences matter for tax. In one, your BTC is locked by Bitcoin's own rules and you keep an enforceable claim on it. In another, it goes to a named custody firm. In a third, a stranger swaps you a token for it. Those are not the same event, and treating them alike is how people get this wrong.
BOB sits at the least favourable end of that range, and the branding actively works against understanding it.
Start with what the network is. Despite the name, BOB settles to Ethereum, not to Bitcoin. Its own chain records list Ethereum as its parent, and gas is paid in ETH. It is an Ethereum layer 2 that happens to include a component letting contracts verify Bitcoin transactions, which is genuinely useful and is not the same as being built on Bitcoin.
The practical consequence arrives immediately: you cannot pay for anything here with bitcoin. Users turn up holding BTC, bridge it across, and then discover they still need ETH before they can do anything with it.
Then there is how the bitcoin gets across. BOB uses a system where independent parties front you the funds: you send bitcoin on the Bitcoin network, somebody delivers you a wrapped version on BOB, and they keep your bitcoin. That person is a counterparty, not a custodian holding your asset for you. You have swapped one asset for another with a stranger.
On most readings that is a disposal, and it is the clearest case in this whole group of networks. It also fragments your records: which wrapper you receive depends on the route, so one person's bitcoin on BOB can be spread across several different tokens with different costs, each needing tracking separately. For how crypto-to-crypto trades are treated where you file, see the USA crypto tax guide or the UK crypto tax guide.
Manage your BOB portfolio with Kryptos.
Bringing bitcoin across
A service fronts you a wrapped version and takes your bitcoin. That is a swap with a counterparty rather than a self-transfer, and it produces records on two chains.
Keeping several bitcoin wrappers apart
Depending on the route you may end up holding one of several different wrapped bitcoin tokens. They are separate assets even though they all represent bitcoin.
Delegating BOB tokens
Delegation does not hand over your tokens, so it is not a disposal, but any rewards it produces are income.
Audit-ready, automatically.
Once your wallets and exchanges are connected, generating a tax report takes a single click. Open Reports from the menu, choose your jurisdiction, and download.
Bridging bitcoin in is a swap
You give bitcoin to a service and receive a different, named token in return, from a counterparty rather than a custodian acting for you. On most readings that is a disposal of the bitcoin and an acquisition of the wrapper.
Gas is an ETH disposal
Fees come out of ETH. Anything pricing your BOB fees against bitcoin is using the wrong asset.
Different routes give you different assets
The wrapper you receive varies by route, so one person's bitcoin position on BOB can be split across several tokens with separate costs. They cannot be merged into one line.
An unclaimed airdrop is nothing
Claims closed on 4 January 2026 and unclaimed tokens were forfeited. If you never claimed, you never received anything.
Points can arrive long after you earned them
Some applications handed out their rewards retrospectively, so the date you received something may be much later than the activity that earned it. The receipt date is what counts.
Read-only by design.
- Kryptos only ever needs your public wallet address
- A public address is read-only. It can't move or spend anything
- We never ask for your recovery phrase or private key
- Remove a wallet whenever you like, and its data goes with it
If something doesn't sync.
You need ETH, not bitcoin. BOB charges gas in ETH despite the Bitcoin branding.
That is the wrapper the bridging service gave you. Which one depends on the route you took.
Every block on this kind of network contains an automatic system transaction that is not yours. Kryptos ignores those; explorer totals do not.
Still stuck? Email support@kryptos.io or open live chat from the app.