You can [1] create a transaction that destroys those coins (spends them on fees, sends them to a charity or really takes them out of circulation) at some time i

You can [1] create a transaction that destroys those coins (spends them on fees, sends them to a charity or really takes them out of circulation) at some time in the future (using nLockTime [2]) in such a way that it could be replaced with another transaction before that time (using a low sequence [3]). [1] In the future, its not all active yet [2] https://en.bitcoin.it/wiki/NLockTime https://en.bitcoin.it/wiki/NLockTime https://en.bitcoin.it/wiki/Protocol_specification#tx https://en.bitcoin.it/wiki/Protocol_specification#tx [3] http://bitcoin.stackexchange.com/a/2032 http://bitcoin.stackexchange.com/a/2032