The National Farmers Union has accused the government of “betrayal” over changes to inheritance tax as thousands of farmers prepare to gather in London for a rally.

Its president Tom Bradshaw told the BBC the measures announced in last month’s Budget were “completely unjust”.

From April 2026, inherited agricultural assets worth more than £1m, which were previously exempt, will be liable to the tax at 20%, half the usual rate.

Environment Secretary Steve Reed said: “We’ve had to ask those with the broadest shoulders to pay a little bit more”. He said that the vast majority of farmers would “pay nothing” even after the changes.

The NFU has gathered 1,800 of its members in London for a lobby of MPs on Tuesday.

A larger event, which organisers say more than 10,000 people have registered for, is being held in Whitehall.

The number of farms that could be affected by the inheritance tax change is disputed.

The government says it will only affect the wealthiest 500 estates each year but the NFU and the Country Land and Business Association (CLA) have estimated up to 70,000 farms could be affected.

Mr Bradshaw told BBC Newsnight: “These are people’s lives, these are people’s livelihoods we are talking about. They have no ability to plan.”

Richard Jowett, who runs a 300-acre farm just outside Salisbury, told Today that according to the Budget announcement his farm would not be affected, but he believed it would.

He said he would have to pay half a million pounds in tax if he one of his children wanted to take it over after he died.

“You feel totally let down,” he said.

Among those attending Tuesday’s events is Gloucestershire livestock farmer David Barton, who has a 265-acre farm near Cirencester that has been in his family since 1913.

He estimates his 400-cattle business is worth around £5m and the proposed changes to inheritance tax could see his son facing a £800,000 bill.

“This budget has just ripped the heart out of us because I know my son will not be able to pay the inheritance tax,” he said.

He is now considering gifting his estate, which means it would fall outside of inheritance tax if he does not die within seven years, but feared he was not in a financial position to stop working.

Baroness Minette Bridget Batters, a farmer and ex-NFU president, has called measures to protect farmers from additional costs.

She told Today it felt like “the penalties just continue to grow” for farmers, with the rise in the National Living Wage, National Insurance hikes and now the inheritance tax.

Environment Secretary Steve Reed said “It’s only right to ask the very wealthiest farmers and those wealthy individuals who have been buying up agricultural land to avoid their own inheritance tax liability, to pay their fair share”.

He added that the government was committed to investing £5bn in sustainable farming over the next two years and said farms will be passed on from generation to generation.

Student Alaw Jones, who is planning to join the rally in London later, is the ninth generation of her family to farm livestock in west Wales. She said her parents had always planned to hand down the business to her and her sister but now “all the work they have done to build the business and get this farm to stand on its own just feels like it’s for nothing.”

She added: “Mental health is a massive issue in the agricultural industry and this feels like the final nail in the coffin for those farmers who are already struggling.”

Rupert Dale’s family run a hay farm on the Worcestershire/Shropshire border supplying livestock farmers across the country.

He said the family now fear they will have to sell up, explaining: “Me and my brother would have to pay an immense sum for our farm to carry on and that’s a sum that we spoke about together as a family that we would not be able to finance and afford.”

Students’ Union president Alexandra Godfrey said: “I think this is one of the most pressing challenges in the farming sector and we all need to rally together to tell the government how we feel. If not now, when?”

Shadow environment secretary Victoria Atkins said Labour had delivered a “budget of broken promises” that was “killing British farming”.

“Farmers can be asset rich, but cash poor,” she told the BBC.

“They are not in it for the money – it’s a 365 day responsibility.”

The Liberal Democrats said it was “utter rubbish” to say only 500 of the UK’s wealthiest farmers’ estates would be affected each year.

The party’s environment spokesman Tim Farron told BBC Breakfast: “The only way that people can pay the inheritance is get rid of the farm – so corporates buy it.

“It’s cruel, it’s unfair, it’s also incredibly stupid”.