Debra Allcock Tyler, chief executive of the training and publishing charity the Directory of Social Change, has called on the government to provide more funding for the Charity Commission in order to avoid charities being charged for its services.
In a letter to Philip Hammond, the Chancellor of the Exchequer, Allcock Tyler says the DSC "and many other charities vigorously oppose plans to charge charities for their own regulation".
The letter calls on the Chancellor to "not go down this road" and asks that he find a viable funding settlement for the regulator out of general taxation.
The commission has been considering the idea of charging charities for regulation so it can cope with its budget being roughly halved in real terms in recent years. A consultation on the subject is due to be published soon.
But the letter says few sound arguments have been put forward in favour of seeking funding from charities, apart from that charities might receive a better service from the regulator.
Allcock Tyler says fees for charities "are wrong in principle" because they would siphon off charitable donations given by the public.
"Donors don’t give to charity expecting that a portion of their donation will subsidise statutory agencies," the letter says.
It warns that fees would be a "damaging burden on charitable resources" and could lead to distorted regulation, with the commission open to criticism for being influenced by large charities responsible for a significant part of its budget.
The process of charging charities would incur costs and would represent poor value for money, the letter says.
"I strongly urge you to find an adequate settlement for the Charity Commission which does not involve charging charities," the letter concludes.
"The commission’s work is critical to the effective functioning of hundreds of thousands of charities across England and Wales. Adequately funding it via general taxation is in the country’s best interest."