The General Medical Council has warned that any locum doctors engaging in “unreasonable withdrawal” from work could exacerbate pressure on health services and potentially risk patient safety.

The medical regulator’s warning follows reports from several NHS trusts of staff cancelling shifts at short notice, in response to the implications of new tax rules.

GMC deputy chief executive Susan Goldmith said locum doctors should “give sufficient notice in line with their contractual agreements” before cancelling shifts.

“Our chief concern is patient safety,” she said.

“In this way disruption to patient care and risk to patient safety can be minimised, and doctors can adhere to our core guidance for the profession.”

GMC’s good medical practice guidelines states that doctors are required to complete a shift to which they have committed, if failing to do so could compromise patient safety.

“Patient safety may be affected if there is not enough medical cover. So you must take up any post you have formally accepted, unless the employer has reasonable time to make other arrangements.”

On Wednesday, Lincoln County Hospital was just hours from closing its A&E after locum doctors cancelled their shifts over a pay dispute related to the IR35 tax changes that came into force on Thursday.

Derby Teaching Hospitals Foundation Trust has said two of its A&E locum doctors gave just two days’ notice before cancelling shifts over the tax changes. The trust is considering whether to refer the doctors to the GMC.

Now a second trust has told HSJ it is considering referring “a small number of locums doctors” who refused to work over the tax changes despite having shifts booked.

University Hospitals of Leicester Trust medical director Andrew Furlong said the doctors had demanded a pay rise to compensate for the tax change. When the trust refused, the doctors cancelled their shifts.

“If we have a situation where a doctor refuses to work despite being booked onto a shift, we are looking at the circumstances on a case by case basis and where we feel a doctor has breached the GMC GMP guidance in regard to compromising patient safety by a short notice cancellation, we will make their Responsible Officer and the GMC aware of our concerns.”

Under the new IR35 rules, “off payroll” workers in the public sector must pay the same level of tax and national insurance as substantive employees. NHS providers will be responsible for ensuring the correct rates are applied. Locums claim the changes leave them worse off and without employment rights as they must pay extra costs to cover sickness, travel, accommodation and pension.

The impact has gone beyond doctors and nurses, to affect a wide range of non-clinical contractors that work with the NHS.

HSJ reported on Tuesday that a group of IT contractors walked away from a multimillion-pound contract at Guy’s and St Thomas’ Foundation Trust rather than accept the new rules.

HSJ has since learned that an IT contractor at Salford Royal Foundation Trust, one of the most digitally advanced NHS trust and a nationally designated “global digital exemplar”, had also walked off the job over the tax changes. It is not believed the loss has had a substantial impact of the trust’s digital work.

Other trusts have also since come forward to confirmed the tax changes have affected them, including The Dudley Group Foundation Trust. A spokesman said: “As expected we have a small number of gaps in our rota which we have been planning for over the last few months with our staff to ensure we continue to provide safe, effective care.”