Satoshi
Also known as: sat, sats
The smallest unit of Bitcoin, equal to one hundred-millionth of a BTC (0.00000001 BTC).
Definition
A satoshi ("sat") is the smallest divisible unit of Bitcoin: there are 100 million satoshis in one BTC. It is named after Bitcoin's pseudonymous creator. For tax it is simply a precision unit — when reconstructing base cost and proceeds, amounts may be tracked to the satoshi to keep calculations exact, especially for fees and small transfers.
Example
A R10 Bitcoin tip might be recorded as a few thousand satoshis; tracking at this precision keeps tiny disposals and fees accurate.