In his budget announcement on Wednesday March 8th, the Conservative Chancellor announced a National Insurance rise for the self-employed.
The changes would see contributions from self-employed people earning between £8,060 and £43,000 increase by from 9% to 10% in April 2018, and from 10% to 11% in April 2019.
It is set to have a particularly big impact in Brecon & Radnorshire.
Figures from the Office of National Statistics show that 9,400 in Brecon & Radnorshire were self-employed in October 2015 - September 2016, the highest number of any Welsh constituency.
29% of all people aged 16+ in Brecon & Radnorshire are self-employed, the second highest percentage of any Welsh constituency.
The FUW has warned of the impact the rise will have for farmers, saying "this increase will hit farmers across the UK badly".
The rise comes despite a Conservative manifesto pledge to not increase National Insurance contributions.