The legislation was introduced in 2006 to ensure charities and donors do not exploit tax loopholes around large donations.
But HMRC has proposed changes after the law was criticised by accountants, tax experts and lawyers for being complicated, burdensome and almost impossible to obey (30 July, page 9).
Kingston Smith accountant Nick Brooks, head of the charities technical group at the Institute of Chartered Accountants, is due to meet HMRC this week to discuss the legislation.
He said the ongoing review of the rules, which finishes on 7 October, does not go far enough, but he expects a more wide-ranging consultation.
He said: "HMRC seems to have taken on board our concerns, so I think it will reconsult."
An HMRC spokeswoman said it was open to holding a second consultation, but would wait to see what the first one brought up.