Mr Banks has faced questions over his relationship with the internet tycoon _ currently facing an extradition hearing on charges of criminal copyright violation - after it emerged that his failed 2010 Super City mayoral campaign got $50,000 from him.
The questions intensified after claims by Dotcom that Mr Banks asked him to split the donation into two lots of $25,000 so they could be made anonymously.
And Mr Banks faced further challenge after it emerged he had lobbied a government minister on Dotcom's application to buy property.
Opposition MPs have called for Prime Minister John Key to stand Mr Banks down as a minister while police investigate complaints Mr Banks declared the donations anonymous
when he in fact knew who made them.
The holiday trip was revealed by the Weekend Herald, which detailed how Mr Banks had telephoned Dotcom's bodyguard to ask for a hotel recommendation.
Dotcom, who has rented the top floor of the Grand Hyatt for seven years, suggested Mr Banks stay at the hotel and helped to make arrangements for the holiday.
Mr and Mrs Banks were collected by limo from the airport, taken to the hotel and later used the limo to travel to the ferry terminal for a trip to Macau.
Late last night, the minister's office sent the Herald a receipt showing that Mr Banks paid for the limo himself.
Earlier in the day, Prime Minister John Key was quizzed in Parliament over whether Mr Banks had got a discount on his Christmas holiday to Hong Kong.
Labour MP Trevor Mallard asked if Mr Banks had told the Prime Minister or his office that "Mr Dotcom facilitated a discount for personal accommodation for Mr Banks at the Hyatt in Hong Kong while Mr Banks was a minister?''
"If so, did he or his office ensure that Mr Banks was properly briefed on the requirement to declare that discount on his Declaration of Pecuniary Interests?''
Mr Key said Mr Banks had not to the best of his knowledge told him about discounted accommodation "but my chief of staff has said to me that Mr Banks has made an assurance that he paid for all expenses on the trip to Hong Kong''.
Mr Key also said he had still not spoken directly with Mr Banks about the matter. "I don't need to. I've had a cast-iron assurance from him that he complied with the Local Electoral Act and that's good enough for me.''
Under Parliament's rules, MPs must declare any gifts with a value of over $500. Any gifts over $500 received in December should be in the next Register of Pecuniary Interests, which should be released this month.
Mr Banks would have the opportunity to amend the declaration, if it emerges there was a discount and if it was decided it should be declared.
Last night, Mr Banks' staff insisted there was no discount attached to the hotel stay. A spokeswoman said she was present when Mr Banks sought and received an assurance there was no discount attached to his bill.
She said Mr Banks asked specifically if there was any discount applied to his bill and was told by the hotel manager there was not.
Mr Banks had earlier sought a copy of the bill from the hotel showing he and his wife were billed HK$4290 ($679) a night for four nights' accommodation. "I was absolutely pedantic about paying for everything in Hong Kong myself and the management of
the Hyatt Hotel will attest to that.
"It was a very expensive week and I paid it all with my wife's credit card.''
The invoice showed Mr and Mrs Banks arrived on Christmas Day and stayed until December 30. The total bill for the holiday was $2879.
Staff on the hotel reservation desk identified the room the couple had stayed in - room 2317 - as one of the Grand Deluxe Harbour View rooms.
They said the room rate was currently HK$7500 plus a 10 per cent service charge. The total figure in New Zealand dollars was $1303 a night.
The rate for staying over Christmas would be higher because it was the peak season, staff said.
The Hyatt website offers a discounted price of $805 for guests that pay for their stay on arrival. The invoice provided by Mr Banks showed the bill was settled on check out.
