A Tauranga couple carried out a "sustained and calculated dishonest course of conduct" over a 12-year period to defraud the ACC, the Crown said on the closing day of the trial.

But in closing, the defence argued the Crown had simply attempted to discredit Grant and Lorraine Brennan by presenting evidence that did not make sense.

The couple, who have been on trial in Tauranga District Court over the past seven weeks, have denied 88 charges of using a document for pecuniary advantage.

The charges stem from an allegation that the directors of Brennan Racing Limited received more than $720,000 in ACC payments between December 1999 and September 2011 which they knew they were not entitled to. That included $52,000 in attendant care payments which were paid to Mrs Brennan between 2000 and 2003.

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On April 24, 1999, Mr Brennan was assaulted by three youths while out running with his wife and son and suffered a head injury.

During his closing address yesterday, Crown prosecutor Richard Jenson told Judge Glen Marshal there was overwhelming medical, business and motor racing evidence that proved the prosecution's case.

Despite claims of a diminished level of functioning, in all areas of Mr Brennan's life he continued to perform "normally and proficiently" - that included resuming working in the business within six months of the assault, and his motor racing activities, he said.

Mr Jenson said some witnesses gave evidence of Mr Brennan having "under-performed" in medical assessments and submitted medical certificates which stated he was unfit for fulltime work.

This was contrary to numerous witnesses giving evidence about their interactions with Mr Brennan, some who said he was engaged to carry out specialist mechanical work on their cars, he said.

Mrs Brennan helped to "perpetuate the lie" by dishonestly claiming attendant care payments, he said.

Mr Jenson said the defence suggestion that the business continued to operate without meaningful input from Mr Brennan, "flew in the face" of the evidence given by many customers.

Defence lawyer Cate Andersen hit back at what she described was the Crown's attempts to "discredit" the Brennans.

"Mr Brennan rejects any suggestion that he was a malingerer ... He has maintained consistently that he did not want to be an ACC beneficiary and if it had not been for the assault the business would have been significantly bigger and more profitable," she said.

Ms Andersen said at all times the Brennans were "open and frank" with ACC, doctors, the medical assessors, occupational therapists and any improvements were also reported to ACC .

"Mr Brennan's evidence and the whole defence case cannot be rejected on any objective analysis. At very least, your honour, you would be left with doubt of their guilt," she said.

Judge Marshall reserved his decision.