Conservative conference: Theresa Villiers gives speech
The secretary of state has said there are still significant issues to be resolved before corporation tax could be devolved to the NI Assembly.
Theresa Villiers was making her first address as secretary of state to the Conservative Party conference in Birmingham.
She also told the Conservative Party Conference that terrorists would not succeed.
She added that Northern Ireland's future is better in the union.
"Like the prime minister, I'll never be neutral in expressing my support for the United Kingdom," Ms Villiers said.
"We are in no doubt that England, Scotland, Wales and Northern Ireland are stronger together, weaker apart."
She said there was widespread support for devolving the power to set corporation tax rates to the assembly to enable more effective competition with the Republic of Ireland.
"I can see the case for this change and it's a case I'm discussing with my colleagues in government," Ms Villiers said.
"However, there are still significant issues to overcome before the government could decide in principle whether or not to proceed.
"Like my predecessor, Owen Paterson, I've been working with Treasury and Northern Ireland Executive colleagues to see if we can resolve these."
Ms Villiers also told Tory activists that those who use violence act in defiance of the will of the people of Ireland.
"I have a clear and simple message for those terrorists - you will not succeed," she said.
"The future of Northern Ireland will only ever be decided by democracy and consent, never by violence.
"For my part, I'll do everything I can to keep the people of Northern Ireland safe and secure."
Ms Villiers was appointed secretary of state last month following a cabinet reshuffle.
Her speech came on day two of the Conservative Party conference.
Thousands of Conservative supporters and activists are in Birmingham for the four-day Conference.
Outside the conference complex, Conservatives were to be lobbied by friends and relatives from Ballymurphy in west Belfast, where 10 people were killed in August 1971 by the Army.
Campaigners want an inquiry and hope the prime minister will meet them.
In a BBC interview David Cameron did not rule out such a meeting.
"I will have to look at my calendar and how much time I have to do all the different things. But I understand the strength of feeling about the case as about so many cases from the deeply troubled and difficult past of Northern Ireland," he said.
The Conservative Party conference ends on Wednesday following Mr Cameron's speech.
The people who were shot dead by the Army in Ballymurphy included a priest and a mother-of-eight.
The Army said it fired in response to shots from republican paramilitaries.
The victims were killed over three days by paratroops during Operation Demetrius, when people suspected of paramilitary activity were interned.
In June, relatives of those killed said Secretary of State Owen Paterson told them an inquiry was "not in the public interest".
Last November, Attorney General John Larkin announced new inquests would be held into the Ballymurphy killings.