HM Revenue & Customs should extend the period charities have to get used to a new online Gift Aid system by an additional six months, according to charity infrastructure.
Charities will be given until 30 September to make the transition from the current paper forms to the new system.
However, at a meeting last week the National Council for Voluntary Organisations asked HMRC for this to be extended to a whole year.
Charlotte Ravenscroft, policy manager at the NCVO, said: "It’s good news that charities will be able to claim Gift Aid online in the future. And for many charities, these changes will be straightforward. But, for some, they will require the adaptation of databases and IT systems, which takes time and money.
"We’ve asked HMRC to extend the transition period to a full financial year – April 2014 – so that charities have more time to make these changes."
She said this might mean that HMRC has to dedicate more resources to the managing the transition initially, but that it would benefit from smoother implementation in the long run. "The prospect of charities being stuck and unable to claim Gift Aid in October is not an appealing one," she said.
Kat Smithson, a policy officer at the Charity Finance Group, also said her organisation would prefer a year’s transition period. "At the moment, we don’t know how simple it will be," she said. "We don’t know how many teething problems there will be in the system.
"Ideally, we’d like a year-long period. Certainly, if organisations haven’t managed to transition by September, we would like HMRC to treat them leniently."
Daniel Fluskey, head of policy at the Institute of Fundraising, said: "We believe that the majority of charities will make the move successfully by the end of September, but where some encounter difficulties we are asking HMRC to offer them flexibility."
A spokesman for HMRC said: "We have already extended the period we are able to accept the old forms. We will listen to concerns if people think they need longer but cannot commit to accepting old paper forms past 30 September."