An official timetable for clearing planned care waiting lists over the summer has sparked concern among NHS managers.

Guidance seen by HSJ indicates that clinical commissioning groups and providers have been strongly encouraged to carry out the required additional treatments by the end of the month.

It also suggests that most of the £250m made available by the Department of Health in June to cut elective lists over the summer should also be expended within the same timeframe.

It stated: “Whilst the money that is being made available can be spent on treating extra patients up until the end of March 2015, we expect the majority of work to be done between now and the end of August.”

Such a strategy would ensure national referral to treatment targets could be met from the start of September, the guidance added.

“Given the pace at which this extra work will need to be done, we are clear that strong and achievable local plans will need to be in place backed up by weekly [list] monitoring.”

Guidance in an earlier official paper in June stated that “all three [referral to treatment] operational standards” should be “achieved in the September 2014 [referral to treatment] data (published in November 2014)”.

Several senior NHS figures told HSJ that treating the required number during July and August – when many staff and patients are on holiday – would be extremely difficult or impossible.

Rob Findlay, founder of the waiting times software company Gooroo, said the action was being taken “a bit late and in a tearing hurry”, and it had been “absolutely clear for a year that the waiting list is growing”.

He said: “Most people go on holiday in July and August. Whether it is actually achievable [to treat enough patients in that period] is very much open to question.

“It would be more robust for backlog clearance to also allow September and October.”

Meanwhile, some senior commissioners told HSJ they agreed with the health secretary’s request this week that long waiters were treated as quickly as possible, and that providers should not have allowed lists to grow in the first place.

Health secretary Jeremy Hunt highlighted the drive to cut lists in a speech on Monday. “More than 100,000 extra treatments” would be carried out “over the summer”, the DH said.

A statement said: “This means that over the next few months… there will be a managed breach of the [referral to treatment] target. However, by the end of the year the NHS will start meeting the target again.”