At first glance, an exchange looks like the easiest place to receive mining income: the account already exists, the address is ready, and liquidity is one click away. That convenience hides one of the most common and expensive mistakes a miner can make. This is not about whether you trust Kraken, Binance, or any other operator. It is about how the system is built.

Technical incompatibility: XMR subaddresses are not valid for mining

Monero has three address types: primary address (starts with 4, 95 characters), subaddress (starts with 8, 95 characters), and integrated address (starts with 4, 106 characters). Standard pool software — including OwnBlock — can only reliably build coinbase outputs to a primary address. Subaddresses and integrated addresses do not fit the direct coinbase payout flow: the pool will reject the address before it builds the candidate block. Most major exchanges, including Kraken, assign subaddresses (starting with 8) as each user's deposit address. If you enter one of those addresses in your miner or in the OwnBlock order form, the system will reject it. This is not an arbitrary OwnBlock rule. It is a mining-software incompatibility: no pool implementing direct coinbase payouts can reliably pay a block reward to a subaddress.

Why an exchange deposit address can change without warning

Exchanges rotate deposit addresses unilaterally. In institutional custody, that is normal practice: addresses are reassigned for technical reasons (UTXO consolidation, infrastructure changes, system migrations), compliance policies (AML, key rotation), or simply because the deposit system generates a new address for each session. Your miner, meanwhile, may remain configured for weeks or months with an address the exchange no longer assigns, monitors, or credits correctly. Rewards can keep going to that destination without ever appearing in your account. The exchange does not have to warn you.

Compliance engines can flag and reject coinbase transactions

A coinbase transaction is the first transaction in each block: it creates new currency directly from the protocol. For many exchange AML/KYC engines, that origin is awkward. There is no prior traceable history, and the funds come from newly minted supply. In practice, the deposit may be classified automatically as high risk. Some exchanges hold these deposits for days or weeks while a manual review runs. Others have rejected them permanently, sometimes returning the amount minus fees and, in reported cases, not returning it at all. This is not an academic risk: it has happened to real miner funds on top-tier exchanges.

Delegated custody: at deposit, the funds leave your control

When a coinbase transaction pays an address you control, the position is clear: you hold the private keys and can spend the funds once they mature. If the address belongs to an exchange, that assurance disappears. You never held the keys. The reward enters the exchange's control directly, and the exchange can credit, hold, freeze, or cancel that balance under terms of service that may also change without notice. The "not your keys, not your coins" principle is not a slogan here. It is the point at which control over the reward is decided.

An account freeze can halt your mining income indefinitely

Mining produces continuous, unpredictable income: a block can arrive at any moment. If your exchange account is frozen — because of a failed KYC check, a regulatory request, legal action against the exchange, an algorithmic fraud suspicion, or an internal error — every block found during that period goes to an account you cannot access. The industry's history is full of users who waited months or years to recover frozen funds, if they recovered them at all. FTX, Mt. Gox, QuadrigaCX, Cryptopia: none of those customers expected their last normal sign-in to be the last time their funds were available.

Your mining address can identify you on-chain

Every coinbase transaction is recorded permanently. If you mine to an exchange address tied to your KYC identity, you create a durable link between your mining activity and your verified identity inside that platform. On BTC and BCH, where the chain is fully transparent, an outside observer can cross-reference blocks, mining times, and addresses to reconstruct a detailed profile of your operation. You do not control that reading. In mining, the address you choose also acts as an operational identity.

The right approach: self-custody from the first block

  • Generate a receive address from a hardware wallet (Trezor Safe 3/5, Coldcard, Foundation Passport). The private key never leaves the physical device.
  • Configure that address as your mining address at the pool. It is the address OwnBlock inscribes in the coinbase transaction of every candidate block.
  • When you find a block, the reward arrives directly at your hardware wallet, without an intermediary.
  • After the maturation period (XMR: ~2h, BTC/BCH: ~16-17h), the funds are under your exclusive control.
  • If you want to sell or convert, start that process yourself from your wallet: send the exchange only the amount you choose, at the time you choose. Never the other way round.
  • Use watch-only wallets (Electrum, Feather Wallet, Sparrow) to monitor balances without exposing private keys.

If you are setting up a miner on a pool today, review our custody and wallet guides before you connect the address. Fixing this now is far cheaper than discovering the problem after you find a block.