Primary care trust directors are being warned not to move into new cluster roles without firm assurances about pay and job descriptions.

The warning comes as many PCTs are implementing instructions issued by NHS chief executive Sir David Nicholson before Christmas to group into clusters by June in order to maintain management capacity during the transition to the new commissioning system.

The quicker we do it, the more mistakes we’re going to make

Sir David’s letter said managers taking on additional responsibilities throughout the transition could be encouraged to stay by being offered special payments.

But Managers in Partnership chief executive Jon Restell has warned that directors should not accept a new position on a cluster’s executive board before ensuring their new salary has been signed off by the Treasury.

The Treasury has to sign off NHS salaries of more than £142,000 and MiP fears it will block additional payments for higher earners.

He said: “We have some reservations about the way the Treasury might respond. People will have to be very careful.”

Directors should ensure they have a full job description before agreeing a move, he said, adding that it was still uncertain how appointments would be made.

Sir David’s letter said appointments had to follow a “fair and transparent process”, and national guidance is due to be published this month.

However, many readers on have complained that appointments to national transition roles and cluster positions are being made before this guidance is available.

Mr Restell said: “The quicker we do it, the more mistakes we’re going to make. The problem with rushed [human resources] processes is they generate individual legal claims.”

In the meantime, Sir David has written this week to chief executives of strategic health authorities, PCTs, ambulance trusts and arm’s length bodies about 2010-11 bonus payments.

As previously announced by prime minister David Cameron, only the top 25 per cent of performers will be eligible for performance linked pay awards.

But the letter reveals that instead of each organisation paying its own top performers, the 25 per cent limit will apply per cluster, rather than per PCT. Similarly, SHA very senior managers must be in the top 25 per cent across all SHAs, as opposed to just within their own organisation.

It is therefore possible that in some SHAs no bonuses will be paid. New pay committees may need to be formed to judge who is eligible, the letter adds.

However, there are concerns about the lack of an agreed system for comparing very senior management performance between organisations and regions.