Westpac will pay a margin of 2.3 per cent over the 90-day bank bill rate on its new subordinated note issue.Yesterday, the bank issued a revised prospectus for the issue, after completing the book build on Wednesday.It has increased the issue size from A$750 million to $850 million.The margin is at the low end of the range the bank indicated when it launched the offer last week.The notes are Basel III-compliant, which means they include a non-viability trigger. There is potential for them to be converted into ordinary shares. The coupon payable on the notes is a cash coupon without franking credits and is cumulative. The coupon can only be paid if Westpac is solvent at the time and will remain so after the coupon is paid out. The notes have a 10-year, non-call maturity structure. This means they must be redeemed for cash at face value after 10 years.