Tax implications of staking (proof-of-stake) or running a masternode

[squatter]

I'm looking for some general information on the tax implications for US citizens with regard to staking or running a masternode. They are pretty similar. In POS, blocks are minted rather than mined, and the creator of blocks is decided based on coin stake (the more coins you control, the more likely that you will mint any given block). With masternodes, you are paid a percentage of block rewards once you control enough coins (plus some additional conditions).

I know how to deal with the capital gains on the block reward payments. But I'm having trouble determining how the block reward payments themselves should be treated. Is each receipt of a block reward (or pro rata share) considered a taxable event? What kind of transaction is it exactly?

Thanks in advance for any info!

[BlueSword]

IANAL, but it seem to me that each payment would be taxed as ordinary income, provided that the received asset is liquid and there is a well-functioning exchange to determine its fair-market value (in USD).  The IRS FAQ (https://www.irs.gov/pub/irs-drop/n-14-21.pdf) mentions that it might also be subject to self-employment tax if carried on as a business as opposed to a hobby.