Mr Beauchamp took his case to the Employment Relations Authority (ERA).
It heard that an error had been printed in the 2008 contract, in which his annual base salary was inserted into the agreement instead of the amount which represented six weeks salary at that time. He was entitled to $13,430.77, but it was incorrectly stated as being $116,400.
Mr Beauchamp told the authority he had noticed the letter of offer included a redundancy payment which was higher than he had expected, but it did not seem unreasonable given he was receiving a more than $50,000 pay rise.
When he handed in his signed contract to a human resources adviser he commented on the amount, he said, but she joked that if her provision was similar she "would hope, nay seek, to be made redundant".
NZDF said this showed Mr Beauchamp was aware of the mistake and acted in bad faith by not raising the issue with his superior.
But the ERA sided with Mr Beauchamp, saying the "light-hearted response he received did not convey to him that he should query the matter at a higher level".
"I also find the HRA's (human resources adviser) response was likely to have allayed any questions he may have had about the size of the redundancy compensation. I accept Mr Beauchamp's evidence that it did."
The authority ruled that Mr Beauchamp was entitled to receive the full amount, and ordered the NZDF to pay the difference of $73,622 which was owed to him.
Comment was being sought from both parties.