But the announcement so far doesn’t mean job losses for Chicago, which will remain the U.S. headquarters for the insurance/reinsurance company.

“Chicago is the foundation of one of our most important markets, and as the headquarters of the Americas will continue to be central to the success of the firm,” CEO Greg Case said, stressing that it will not cause job losses in either Chicago or the U.S. In fact, Aon said it plans to add more than 1,000 positions across its U.S. operations this year.

Aon has about 6,000 workers in Chicago, and plans to add an additional 750 jobs at the Aon Center in downtown Chicago, where it recently signed a letter of intent for a 15-year lease, the company said in a statement announcing the move.

Aon said the move to the U.K. provides “better access to emerging markets”, as well as strategic proximity to London, “one of the key international hubs of insurance and risk brokerage”.

Aon spokesman David Prosperi told the Chicago Tribune the company made the decision because of the fact that its business was “evolving globally.” While some Illinois companies have threatened to move their headquarters from Illinois over state income tax issues, “we are not doing this for any public policy reasons in Illinois,” he told the Tribune.

The Tribune story does have more details from the Securities and Exchange Commission filing, which indicates that U.S. taxes at least partially motivated the move, too. The company will move its incorporation from Delaware to England.

I recently reported on the incentives game that companies tend to play, including the CME Group and Sears. You can check out that story here.