There is a major difference between Commonwealth Bank's PERLS VIII hybrid notes issued in March, and Westpac's Capital Notes 4, NAB's Capital Notes 2 and the current ANZ Capital Notes 4 issues.New Zealand's interest.co.nz pointed out that the CBA PERLS VIII notes are issued by the New Zealand branch of the bank. The other three issues referred to above are issued directly by the banks themselves.This difference could result in the PERLS VIII notes being redeemed well before their October 2021 call date.Such an event would result in unexpected short term capital losses for investors currently paying up to A$105 in the secondary market to buy the notes with a $100 face value.Issuing through the New Zealand branch provides CBA with a tax deduction for the "interest" paid in New Zealand but allows franked distributions to be paid to Australian noteholders. Thus, effectively tax is avoided in both New Zealand and Australia.Distributions paid by ANZ, NAB and Westpac on their hybrid securities are paid out of after-tax profits, the same as dividends on ordinary shares.  CBA has used this trick with previous PERLS issues and the tactic puts the bank in the same league as Apple, Google and the other big multinationals that use differing tax laws between countries to minimise their tax liabilities legally.Nevertheless, it has been well publicised that countries within the OECD are acting to reduce such opportunities for tax minimisation.And these moves may be occurring faster than what some expect. Section 5.2.7 on page 53 of the PERLS VIII prospectus makes reference to the possible tax changes that would allow CBA to immediately redeem the PERLS VIII. Subject to Australian Prudential Regulation Authority approval, CBA has the right to redeem the PERLS VIII notes upon the occurrence of a tax event. The bank notes that anti-hybrid rules are being developed by the OECD which refer to specific types of cross-border hybrid mismatch arrangements which the PERLS issues employ.  CBA notes that there is no indication that the Australian government will implement legislation that will affect the PERLS VII notes but the New Zealand government is expected to consider the OECD proposals this year.This week the New Zealand government released a discussion paper addressing the OECD proposals for hybrid mismatch arrangements. The paper observes "that hybrid mismatch arrangements are one of the main base erosion and profit shifting strategies used by some large multinational companies to pay little or no tax anywhere in the world."The government is seeking submissions on how the OECD recommendations can be implemented in New Zealand and says it will not make any decisions until after the consultation period has ended. Submissions must be made by October 17. The end is nigh.