Westpac proactively released its submission nearly two weeks ago. It said the new rules could add $6,000 to an Auckland mortgage, as interest rates would need to rise to generate extra capital.
Likewise, a joint submission from the smaller New Zealand-owned banks has been released. Kiwibank, TSB, The Co-Operative Bank, and SBS warned the capital proposals could weaken competition and increase the gap between the Australian-owned big four and other lenders.
TMMOnline approached the other big Australian-owned banks, ANZ, ASB, and BNZ, for their submissions but they chose to wait until the Reserve Bank makes the submissions public.
ANZ's response will face particular scrutiny, after the bank was censured by the RBNZ over its internal capital modelling failings. ANZ has been forced to adopt a standardised model for its capital buffer, and needs to hold an extra $277 million aside, after admitting to internal failings.
Financial analysts believe the new capital rules will have a significant effect on the banking landscape.
While Forsyth Barr believes the rules will "level the playing field" between big and smaller banks. The firm believes the rules will be a "catalyst for ownership and structure changes", as small banks look to take advantage.
The consultation period for the capital proposals closed in May. A Reserve Bank spokeswoman confirmed submissions would be released this month, but said it has not yet picked a date.
Its proposals could force banks to increase their capital buffers by 20%-60% to guard against risk in the financial sector. The central bank estimates the extra buffer would account for 70% of banks' profits over a five year transition period.
The Reserve Bank has looked at capital rules since early 2017. Deputy Governor Geoff Bascand says the proposals are designed to make banks more "resilient to shocks that might occur only once every two hundred years".
The proposals would make New Zealand's capital adequacy regimes one of the toughest in the world. The consultation has sparked fears they could lead to increased mortgage rates.