The letter from Premier Peter Gutwein to Independent member for Mersey Mike Gaffney contains a four page analysis of the bill which raises concerns about its drafting and implementation.

Mr Gutwein says he asked the Department of Premier and Cabinet to seek feedback from government departments on "any implementation challenges" if the bill is passed and becomes law.

"In providing the feedback I note that departments have had limited time to review (the) bill and there may be other matters that come to light in the future so I would recommend that you obtain further external advice on the matters raised," he wrote.

"The feedback is provided for information purposes only. It does not in any way indicate that individual members of the government support or do not support the bill."

Mr Gutwein says in the interest of informed debate he would make the information available to all MPs.

The analysis of the bill says it is long and complex.

"The introduction of voluntary assisted dying provision potentially poses significant risks to patients, in the context of their care, and to medical professionals, in the context of delivering services and therefore every effort needs to be made to confirm the bill contains provisions that protect patients and restrict professional liability," it said.

The analysis questions the cost of funding a Commissioner of Voluntary Assisted Dying and support staff to implement, administer and review the legislation.

"The implementation time-frame of up to one year under current circumstances is insufficient," it said.

"Government departments have significant existing resources allocated to responding to COVID-19, which has an unpredictable future."

It also raises issues around the incorrect diagnosis of a medical condition and decision making by people with disability.

"A medical practitioner may incorrectly diagnose a condition if they are not particularly skilled for certain medical conditions, and there does not seem to be any obvious requirement for this criterion to be assessed by a suitably qualified person.

"The most significant element in the bill for people with disability will be how 'decision making capacity' is determined."

The analysis also said: "The bill may leave the status of a person's insurance policies unclear and this needs further consideration."

The bill is due to begin being debated in the Legislative Council on September 15.