It also recommended placing an upper rateable value (RV) limit on retail premises eligible for charity relief, introducing tighter qualifying criteria, limiting the number of retail units eligible for charity relief in a given town or area, and making rate reliefs available to social enterprises such as credit unions which are currently not eligible.
The Charity Retail Association was responding to the report on business rate relief for charities, social enterprises and credit unions presented by the Business Rates Task and Finish Group to the Welsh Government last month.
In the report, which forms the basis for a consultation, the Task and Finish Group chaired by Prof Brian Morgan recommended limiting rate relief to 50% for larger charity shops trading in new goods.
She said: "We estimate that the proposals to reduce rate relief from 80% to 50% for all charity shops could cost them PS1.
In addition, this report by the Task and Finish Group simply doesn't have the support of the public in Wales: our petition to the Welsh Assembly had over 22,600 signatures protesting against restricting charity shop rate relief.
This decision on empty rate reliefs for the commercial sector and charities has been made in isolation and will exacerbate the confusion and problems many businesses face.
Property experts last night expressed doubts about the Chancellor's decision to restrict rate relief on empty industrial property and offices and retail space.
Brian Berry, head of UK public policy at the Royal Institution of Chartered Accountants, said: "The Government's decision to restrict rate relief on empty commercial property is concerning.
At the same time we suggested making rate reliefs available to social enterprises, such as credit unions, who currently are not eligible.
But a combination of better targeting of existing rate reliefs and more focused planning decisions could offer a way forward.
EARLIER this month the Western Mail reported that a campaign had been launched by the Charity Retail Association (CRA) against proposed changes in business rate relief for charity shops in Wales.
The first was the increase in rate relief for charities from 50% to 80% in 1990.