When Norm Baker accepted a golden handshake from The Department of the Prime Minister and Cabinet, he trusted his colleagues to get the numbers right.

He was wrong.

Now the Canberra retiree says he has been short-changed by up to $17,000, looks set for a  legal battle against his old department and is urging public servants taking redundancies to double-check the fine print.

Do you know more? Send your confidential tips to ps@canberratimes.com.au Mr Baker was in hospital in April this year, recovering from knee replacement surgery, when his bosses at PM&C called and asked him to consider a redundancy.

"The first offer they gave me was a little over $83,000, then the second formal quote was a little over $80,000," he said.

"So because they'd recalculated and had done the right thing, I thought in the end it might be very close to that number.

"But in my case it was substantially different.

"It's only a modest amount in the scheme of things, certainly compared to others, but it's significant to me."

PM&C have told The Canberra Times that 'human error' was responsible for mistakes made in redundancy packages paid to 37 of its departing public servants, including Mr Baker, but it remains unclear exactly what went wrong.

"I certainly got a shock when I saw my bank account on the day it was paid in and I still didn't get a formal pay slip until two days ago, so I had no idea of how they calculated, or what they'd done," he said.

Now he is back on his feet and enjoying a regular round of golf in his retirement, Mr Baker took a swing at the treatment he received from PM&C.

"I was frustrated and it made me a little bit angry because I'd felt misled," he said.

"I relied on their advice and on their information totally because I'm not an expert in HR by a long shot.

"I was very disappointed when the payment was substantially less than they'd said.

"The disappointing thing was that I was quite emphatic that July 1 was to be the departure date and I told then they should calculate the numbers based on that date.

"Why they didn't, I don't know.

"Were they too busy, or just put in numbers that were wrong? I just don't know."

Mr Baker's advisor, Susan O'Neil, of White Pillar consultants, said the former public servant had been asked by PM&C to sign a waiver if he wanted to leave on July 1 but was not advised of the financial implications of signing the document.

PM&C told The Canberra Times that it would issue apologies and reimbursements to all of its public servants affected by mistakes.