In a letter to Amazon executives that Gilbert attached to the bid, the billionaire mortgage and real estate mogul used a retail sales pitch to the world's largest online retailer, touting "lowest prices," "biggest selection" and "fastest delivery" for office space, much of which has not yet been built.

Complete coverage of the quest for Amazon HQ2

"If you build it, oh, they will come," Gilbert wrote in his letter to Amazon. "... The road has been paved for Amazon. There is no better place for you to innovate and continue to improve the delivery of your customer experience."

Details about the bid, which was submitted to Amazon by a Gilbert-led regional committee on Oct. 19, have been largely shrouded in secrecy until now.

The proposal to Amazon and its CEO, Jeff Bezos, says the company could operate for 30 years without paying real estate and personal property taxes, the city of Detroit's 2 percent corporate income tax or the city's utility users tax under the state's Renaissance Zone Program.

Under the Renaissance Zone Program, Amazon would still have to pay local property taxes for public debts, such as school buildings. Prospective Amazon employees would still be subject to paying Detroit's 2.4 percent income tax for residents and 1.2 percent tax for nonresidents.

Read the executive summary of the Detroit-Windsor Amazon HQ2 bid

The total value of taxpayer subsidies and incentives offered to Amazon remains a secret as Detroit and Windsor await word from the company on whether the binational bid makes a second round in Amazon's selection process.

The summary bid document redacted the estimated dollar value of tax incentives and breaks the state, Wayne County and city of Detroit are offering Amazon to locate its HQ2 in the Detroit under a nondisclosure agreement Gilbert's companies made with the Michigan Economic Development Corp.

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The HQ2 bid summary says Amazon would be eligible to keep 100 percent of the the new state income taxes its employees generate for 10 years and 50 percent of those taxes for the following 10 years, effectively stacking together two different tax-capturing incentives the Legislature approved earlier this year.

A new state law lets companies capture all of their employees' 4.25 percent state income taxes for 10 years if they exceed the regional average pay, which for Detroit is about $58,000 a year.

The tax incentives are "available to Amazon with no further legislative action," according to the summary document.

While Michigan's tax incentive offer to Amazon is being kept secret, the Canadian taxpayer subsidies were disclosed in the bid summary obtained by Crain's.

Windsor is offering Amazon an incentive package valued at $106 million in U.S. dollars through property tax increment financing, grant funding and corporate income tax credits — plus "prime real estate at a nominal cost." Windsor's incentives are based on Amazon locating 5,000 employees in a 500,000-square-feet of office, according to the bid summary.

The proposal also says Amazon could qualify for Canadian corporate tax credits for research and development and innovation tax credits of between 25 percent and 30 percent of expenses if it situates R&D work in Ontario. Crain's first reported in September on the potential tax advantages for Amazon of a binational bid.