US-based Steris to buy UK's Synergy Health, tax savings eyed

* Steris to set up new company incorporated in UK

* Tax rate seen falling to 25 pct 2015/16 from 31.3 pct in 13/14

* Offers 439 pence per share plus 0.4308 shares in new UK company

* Offer valued at 19.50 stg per share, 39 pct premium (Adds details, Synergy Health share movement)

Oct 13 (Reuters) - U.S. medical technology company Steris Corp offered to buy British sterilisation services provider Synergy Health Plc for about $1.9 billion in cash and stock in a deal that would shift its domicile to the UK and cut its tax bill.

Steris said it would set up a new UK company to undertake the acquisition, joining a growing list of U.S. companies that are trying to cut their tax bills by shifting their corporate domicile from the United States.

The new company is expected to have an effective tax rate of about 25 percent beginning in the fiscal year starting April 1, the companies said in a joint statement on Monday.

Steris's effective tax rate for 2013/14 was 31.3 percent.

The allure of smaller tax bills in countries such as Ireland and Britain has prompted at least 10 U.S. companies to attempt so-called "tax inversions" this year.

But the strategy has drawn the ire of U.S. politicians and regulators, resulting a clampdown by the U.S. Treasury last month.

Steris is offering Synergy shareholders 439 pence per share in cash and 0.4308 shares in the new company for each share held.

The companies said the deal valued Synergy at 19.50 pounds per share, a 39 percent premium to the stock's close on Friday.

Synergy shares were up 30 percent at 1,825 pence at 0945 GMT, the top percentage gainer on the London Stock Exchange.

Steris stockholders will hold 70 percent of the combined company, with Synergy shareholders owning the rest.

The new company is expected to have revenue of about $2.6 billion and 14,000 employees in 60 countries.

The deal is expected to cut costs by $30 million or more per year and add to earnings in fiscal 2016, the companies said.

Steris Chief Executive Walt Rosebrough will be the CEO of the new company, which will retain its operational and U.S. headquarters in Mentor, Ohio.

The deal is expected to be completed by March 31, 2015, after which the new company's shares are to be listed on the New York Stock Exchange, the companies said.

Lazard was financial adviser to Steris, while Wachtell, Lipton, Rose & Katz and Jones Day was legal adviser.

Investec Bank Plc was the financial adviser to Synergy. DLA Piper acted as legal counsel.

(Reporting by Roshni Menon and Ankur Banerjee in Bangalore; Editing by Anand Basu)