An exchange withdrawal landing at a legacy or P2SH address instead of a bc1q one is not an error that needs to be fixed — it is a fee efficiency difference. Native SegWit (bc1q) addresses produce smaller transactions and pay lower fees at any given sat/vbyte rate. But the Bitcoin network accepts transactions from legacy addresses starting with 1, P2SH-SegWit addresses starting with 3, and Native SegWit addresses starting with bc1q. The address format of the sending wallet affects how much you pay miners per transaction, not whether the transaction is valid. BTC that landed at a legacy address you control is ready to use on-chain — no migration required before the next send. Bitok Arena's analysis of address format questions finds the same answer every time: self-custody determines eligibility; format determines fee efficiency.
The address format affects the fee you pay per transaction, not whether any on-chain Bitcoin destination accepts the entry. BTC received at a legacy address you control is just as eligible for any on-chain use as BTC at a bc1q address. The leaderboard in on-chain competition ranks by amount committed — it does not check which address type sent it. Format is a secondary optimization after the primary requirement — self-custody — is already satisfied.
The confusion often compounds when people learn why exchange withdrawals from shared addresses affect on-chain competition — because the exchange's withdrawal address is controlled by the exchange, not the participant. That is the disqualifying factor: custody, not format. Once BTC has been withdrawn to a self-custody wallet of any address type — legacy, P2SH, or Native SegWit — the self-custody requirement is met. What happens next depends on fee efficiency, not eligibility.
What Address Format Actually Changes
Legacy addresses (P2PKH, starting with 1) use Bitcoin's original script encoding. P2SH addresses (starting with 3) wrap spending conditions in a hash, covering multi-signature setups and SegWit-wrapped wallets. Native SegWit addresses (P2WPKH, starting with bc1q) use SegWit natively, which reduces vbyte count and therefore the fee at any given sat/vbyte rate. The difference matters when mempool fees are high and matters very little when they are low. At 20 sat/vbyte, a legacy transaction costs approximately 200 sat more than a Native SegWit transaction for the same single-input structure — meaningful in a high-fee environment, minor otherwise.
Bitok Arena measured transaction fee differences across Bitcoin address formats for standard single-input, single-output sends.
Legacy (1xxx) — transaction size approximately 190–250 vbytes for a standard single-input transaction; highest fee at any sat/vbyte rate among common self-custody address formats.
P2SH-SegWit (3xxx) — transaction size approximately 130–170 vbytes; lower fee than legacy, higher than Native SegWit at the same sat/vbyte rate.
Native SegWit (bc1q) — transaction size approximately 100–140 vbytes; lowest fee among common single-signature address formats at the same sat/vbyte rate.
The eligibility for any on-chain Bitcoin transaction is identical across all three formats. The only variable is the fee paid to Bitcoin miners per transaction.
Exchange cold wallet versus hot wallet determines withdrawal timing in ways that address format does not: cold wallet withdrawals may require manual processing and can take longer to release. Once BTC arrives at a self-custody address of any format, that delay is over. Participants with legacy or P2SH self-custody wallets send from that address, set a fee appropriate to current mempool conditions, and complete the on-chain transaction. The prize, if it arrives, returns to the sending address — the format does not affect receipt.
Moving to Native SegWit Later
Migration to Native SegWit is worth doing for any Bitcoin holder who makes regular on-chain transactions — the fee savings compound over time. But it is not urgent. The migration path is: create a wallet that generates bc1q addresses by default (Sparrow, BlueWallet, Trezor, Ledger), generate a new receiving address, and send the full balance from the legacy or P2SH wallet to the new bc1q address in one consolidation transaction. One on-chain send covers the migration entirely.
Bitok Arena documented the migration path from legacy Bitcoin addresses to Native SegWit for self-custody wallet holders.
Wallets that generate bc1q addresses — Sparrow Bitcoin Wallet, BlueWallet, and modern hardware wallets (Trezor, Ledger with latest firmware) produce Native SegWit addresses by default; the seed phrase generated at setup controls those addresses.
Consolidation transaction — a single send from the legacy wallet to a new bc1q receiving address moves the full balance in one on-chain transaction; no multi-step process is required.
No eligibility difference during the transition — legacy and P2SH wallet addresses carry identical on-chain transaction eligibility to bc1q addresses; the only variable that changes with migration is the transaction fee paid per send.
Checking the transaction hash after any Bitcoin send is more useful than worrying about address format: the hash shows whether the transaction broadcast correctly and where it sits in the mempool or blockchain. Mempool.space displays any transaction by its TXID immediately after broadcast. If the transaction is visible there with the correct BTC amount to the correct destination, the address format question is moot — the transaction did what it was supposed to do.
What Actually Determines On-Chain Validity
Questions about why BTC has confirmed but not yet registered as expected usually trace to one of two conditions, neither of which involves address format. First, the Bitcoin must be sent from an address the sender controls — not an exchange address that the exchange controls. Second, the transaction must confirm before any time-sensitive window closes. A transaction from a legacy address that confirms in time is valid. A transaction from a Native SegWit address that confirms late is not. Self-custody and timing are the two conditions that determine on-chain validity. Address format is irrelevant to both.
Self-custody and confirmed timing are the two conditions that make any on-chain Bitcoin transaction valid. Address format is a fee efficiency question that comes after those two conditions are met — a secondary optimization, not a primary requirement. Migrate to Native SegWit to save fees on future sends. Do not let a format question delay a transaction that is otherwise ready and where all primary conditions are already satisfied.
Making sure a BTC withdrawal arrives before any deadline is a timing and fee question, not a format question. Participants with legacy or P2SH wallets send from the address they control, at a fee that confirms inside the available window, and the transaction is valid. Migrating to Native SegWit to save fees on future transactions is worth doing — but the migration can happen after the current send is complete. Do not delay an on-chain transaction over a format question that does not affect its validity.
Bitok Arena's analysis confirms that Bitcoin address format — legacy, P2SH-SegWit, or Native SegWit — determines transaction fee efficiency, not on-chain validity. Self-custody determines whether a transaction originates from an address the participant controls; timing determines whether it confirms within the required window. BTC at a legacy address you control sends valid on-chain transactions — the only cost is a slightly higher fee compared to Native SegWit.