"It is not a perfect agreement but it is a damn sight better than what we had when we started," Ardern said on Saturday afternoon (local time) following the APEC Leaders Summit in Da Nang, Vietnam.
The Investor-State Dispute Settlement (ISDS) no longer applies to investor screening.
Anyone who takes up contracts with the government would have to sue under domestic procedures instead of ISDS and a third aspect has been agreed around financial services.
Those provisions have been suspended, so while they will remain in the deal, a separate side treaty notes that they would not apply unless all nations agreed to re-include them.
As well as the reciprocal agreement with Australia to scrap ISDS provisions Ms Ardern said New Zealand was also continuing to seek side letters with a handful of other countries, but won't detail who they are until an agreement has been ratified.
Trade Minister David Parker says New Zealand has also had wins in suspending patent extensions in relation to Pharmac, something the government believed would increase the cost of medicines.
It's been a turbulent few days for negotiators who are expected to meet again, likely in Japan by the end of the year, to nut out solutions to four outstanding issues.
Canada has suspended a narrow area relating to cultural issues and specifically how the agreement would impact funding for Francophone Netflix programming.
While it's only a very small part of the overall agreement it's believed only New Zealand was amenable to those changes.
Vietnam is seeking exemption periods for sanctions while they raise labour standards to meet international standards required by the CPTPP, while Brunei and Malaysia are seeking changes services and investor and state-owned enterprise provisions.
Ardern will now take the in principle agreement back to parliament where MPs and the public will have the opportunity to scrutinise the changes at the Foreign Affairs, Defence and Trade Select Committee.
New legislation will also need to be introduced to ratify the new agreement.
- NZN