This is when the Chancellor of the Exchequer announces the new government budget and tax policy to parliament and the people.
This year's a little special, because now Labour and young Britiainis left holding the bill and the bag for Brexit and all of Boris's other shenanigans.
Rumours are of increased capital gains tax and inheritance tax, along with an introduction of a gambling tax on winnings (currently tax free), but most degree that there's some bad news coming in the post for people's personal finances.