# isCoinbase `true` if the coin was created by a coinbase (block-reward) transaction. ``` var isCoinbase: Bool { get } ``` ## Discussion Coinbase coins are subject to the 100-block maturity rule: they cannot be spent until 100 additional blocks have been confirmed on top of the block that created them. The kernel enforces this during [`processBlock(_:)`](/documentation/BitcoinKernel/ChainstateManager/processBlock(_:)).