The Charity Retail Association will hand a petition to the Welsh Assembly later calling on it to reject proposals that would see business rate relief for charity shops restricted.
At the moment Welsh charities can enjoy relief of 80 per cent, this could be reduced to 50 per cent for some shops. The Welsh Government closed its public consultation on the issue last month.
In November the association warned the changes could force the closure of a third of charity shops in Wales.
The petition will be presented to William Powell, who is the chair of the National Assembly's Petitions Committee, on the steps of the Senedd.
It reads: "Charity shops make a vital contribution to raising income for a huge range of good causes in Wales. 100 per cent of their profits go to charity, raising over £12 million every year in Wales."
The Charity Retail Association claims that if these proposals go ahead there will be more empty shops on Welsh high streets, 700 full time jobs will be under threat along with 9,000 volunteering opportunities offered by charity shops in Wales.