More than a thousand farmers in Northern Ireland have protested against a new UK tax law they say will "put the lights out" for family farms.
Six rallies are being held simultaneously, one in each county.
Hundreds of tractors are taking to the roads in each location to demonstrate their opposition to the changes which take effect next April.
Protests are also taking place across Britain.
The farmers are angry at inheritance tax changes announced in the last UK budget.
It means for the first time farmers passing land and other assets onto the next generation face a significant bill where previously they were exempt.
They will have ten years to settle the tax demand, but farmers fear those inheriting they will have to sell land to meet it.
The British government has said various exemptions means it will affect only the wealthiest landowners.
But the Ulster Farmers Union which is co-ordinating the day of action says many ordinary family farms will be caught in the tax net.
John McLenaghen, the UFU’s deputy president attended the rally and tractor run in Derry.
"The fear is that some of the farm will have to be sold in order to pay the tax," he said.
"It’s as simple as that, and that will make the farm unviable.
"And if you're looking to pass the farm on, and the next generation is taking it on and they have ten years to pay the tax then over those 10 years, they will work for nothing other than to just pay the tax, and that is not going to incentivise them into farming.
"And that's where we're going to see a mass, we fear, a mass exodus out of our industry."
Among those taking part in the rally today was 20-year-old Amy McCollum from Coleraine who hopes to take on her family’s farm.
She said she was fearful for the future if the law is not changed.
"I'd like to keep the family tradition going, because it's been passed down for generations, and it'd be so sad to have to give up just because the government can’t figure out a way to allow us to keep our land as well," she said.
Also taking part was James Purcell from Limavady and his two-year-old son Jack.
He said he had concerns about his son’s ability to inherit.
"Yes, we might have land, but we're not selling it to cash it in. You know, we're just passing on the next generation. So therefore, why should we be taxed on that passing along the line?
"My father before me passed it to me, my grandfather before that. Like, so it's just, it's really stupid, the way the government have brought this in."
Mr McLenaghen said farmers were happy to pay tax on income but assets had no actual value unless they were sold.
