By Robb M. Stewart 
 

MELBOURNE, Australia--National Australia Bank Ltd. (NAB.AU) would join Scotland's two major banks in shifting south of the border should Scotland vote for independence in a referendum next week.

Registering its Clydesdale Bank subsidiary in England would address some of the uncertainties and risks that surround the still unclear terms of separation if Scotland leaves the union with the rest of the U.K., NAB Chief Executive Andrew Thorburn said in a statement Thursday.

Royal Bank of Scotland Group PLC (RBS.LN) and Bank of Scotland parent Lloyds Banking Group PLC (LLOY.LN) have also said they would redomicile in England in the case of a "yes" vote on Sept. 18.

Mr. Thorburn last month said a vote in favor of independence would bring significant additional costs and risks for Clydesdale. A spokesman for the Australian lender declined to elaborate on the nature of the expected costs or what other contingency plans NAB has in place for Glasgow-based Clydesdale.

Analysts at J.P. Morgan in a research report this week said containing capital and deposits from fleeing Scotland in the event of a vote in favor of independence is the greatest risk to banks in the near term. But longer term, Clydesdale and others could face higher compliance charges to meet new tax and banking regulations in Scotland and might face an increase in loan-loss charges.

Credit Suisse estimated the cost of establishing an England head office for Clydesdale would cost NAB almost GBP41.6 million (US$67.4 million) before tax, while shutting down in Scotland would cost about GBP62.4 million. Added together, that would represent about 2% of NAB's expected pretax profit in fiscal 2015, it said.

Registering Clydesdale in England would be subject to regulatory approval and other requirements, and NAB said the timing and cost would only be determined in due course.

Write to Robb M. Stewart at robb.stewart@wsj.com

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