Farmers have been urged to write to their MPs to highlight the 'devastating personal impact' of the changes to agricultural property relief on their futures.
Making the call is the National Pig Association (NPA), which described the recent autumn budget as having some of the 'most nonsensical policies ever'.
There has been huge backlash to changes that will result in farms facing inheritance tax bills that could force a restructure, or, in some cases, selling the business.
Despite intense lobbying from farming bodies, the Treasury is currently sticking by its line that this will only affect a minority of farmers and landowners.
However, a recent report by the BBC suggested the Treasury had no intention of making any changes to the policy, despite concerns within Defra.
It has been reported that some rural MPs are coming under intense pressure from constituents to oppose the policy.
NPA chairman Rob Mutimer said it was 'vital' that farmers set out their individual cases so MPs could see the 'true impact this policy will have on farm businesses and food security'.
He said: “I urge all members who are affected by this to write to their MPs to show that it is family farms who are going to suffer from this, not rich landowners who can afford it or find ways around it.
“It is absolutely ludicrous to say most family farms won’t be brought into this. I have spoken to many farmers about this, and it is clear that even people with average-sized farms will face inheritance tax bills of hundreds of thousands of pounds.
“Many businesses simply will not be able cope with that and will have to sell off parts of the farm to pay for it, making them and the wider industry less competitive.
“Yes, there are things farmers can do, such as gifting farms to offspring and starting the succession process earlier, but, in many cases that is not straightforward.
"Any family farm that hasn’t got their succession sorted out could be in an absolute mess, unless the government looks again at this.”
The NPA leader said that even if the government didn't scrap the policy altogether, there was a lot it could do to mitigate the worst of the damage for farmers, such as pushing the start back and increasing the thresholds.
“Farmers feel a sense of betrayal after all the assurances we received from the prime minister and Defra ministers before the election on APR and their wider commitment to supporting British farming," he added.
"That all disappeared with this announcement, and I fear the relationship will be permanently damaged unless there is an urgent rethink.”
Mr Mutimer confirmed he would be attending the NFU mass lobbying event on Tuesday 19 November, which has been restricted to 1,800 farmers.
However, he urged farmers to register for a parallel rally that it is expected to be attended by thousands, also taking place on 19 November and in central London.
