But if you want to focus specifically on biomass, I would say: "it depends". You can't answer that question easily. For instance, would you say a biomass plant producing electricity from wood pellets imported from Brazil is carbon-neutral? I think it isn't. When you're looking at biomass, you can't just look at the plant, you need to focus on how its fuel is sourced, what impacts this sourcing activity has, etc.
No; the reason is that this wood is a byproduct of land use change, which is a source of increased carbon emissions [1].
[1]: https://en.wikipedia.org/wiki/Land_use,_land-use_change,_and...
But the carbon cost to manage, process and transport that fuel is not neutral.
Because gasoline for the trucks and coal for the electricity is fossil carbon. Which is not biomass. My point.