As the second round of bids for the sale of the iconic General Motors Building came in yesterday, tongues were wagging in real estate circles over the hundreds of millions of dollars in fees that will be associated with the sale.

Deals of this size — the skyscraper is expected to fetch more than $3 billion, the highest sale price for a single building in American history — come with streams of paperwork, intense analysis, and complicated legal maneuvering. In the end, the owner of the building, Harry Macklowe, and the successful bidder will have pay real estate taxes, lawyer fees, mortgage and commercial broker commissions, property assessments, and other expenses that experts estimate could reach as much as $300 million.

Among the law firms that could benefit from the fees windfall are Skadden, Arps, Slate, Meagher & Flom, and Fried, Frank, Harris, Shriver & Jacobson, sources said. Representatives from the firms did not return calls for comment. Large title insurance companies that may also be linked to the deal include Stewart Title Insurance Co. of New York and First American Title Insurance Co.

“When you are talking about the GM building, you are talking as much as $300 million in fees and taxes and money you have to have up front,” a prominent landlord in the city, who asked not to be identified because of the sensitivity of the deal, said. “It’s beyond enormous.”

The bidders who were expected to hand in their final offers yesterday include Larry Silverstein, who is reportedly backed by the cash-rich California State Teacher’s Retirement System, and Joseph Cayre, who has said that Middle Eastern investors would provide most of the financing for his deal. A third bidder, SL Green Realty Corp., did not submit a second bid, sources said.

The largest cost outside the actual price tag will be the taxes. If the building sells for Mr. Macklowe’s intended price of $3.5 billion, the taxes would total about $114.3 million. The mortgage recording tax, paid by the buyer, would be about $22.4 million, and the real property transfer tax, paid by the seller, would be another $91.9 million.

On top of that, there are the fees charged by a small army of lawyers, financial consultants, building analysts, and brokers.

Two brokers from CB Richard Ellis, Darcy Stacom and Bill Shanahan, are representing Mr. Macklowe on the deal. The size of the final transaction will likely preclude them from taking the standard 1% of the purchase price, but their commission could easily soar to more than $10 million, the chairman of the real estate practice for the law firm of Greenberg Traurig, Robert Ivanhoe, said.

Mr. Ivanhoe represented the seller of the Stuyvesant Town and Peter Cooper Village deal, Metropolitan Life. The sale of 110 buildings totaled $5.4 billion, and was the most expensive real estate transaction in American history. Mr. Ivanhoe said he billed $100,000 on the deal.

“Things get expensive when you have a complicated capital structure,” Mr. Ivanhoe said. “If someone came in and bought the building with cash, it wouldn’t be a problem, but as these deals get larger, the buyer has to use other people’s money. Then you have a whole group of people negotiating joint ventures and agreements.” The tight timeline is also pushing up the number of billable hours, and when multiple senior lawyers are charging as much as $1,000 an hour, those fees can quickly escalate. “I’m sure everyone is working around the clock,” a co-chairman of the real estate department of Gibson, Dunn & Crutcher, Andrew Levy, said. “It’s fast-paced, there are lots of changes every minute.”

The other people accruing fees include title insurance lawyers, mortgage brokers, and due-diligence teams examining the buildings. To appease its lenders, the buyer would also likely have to put six months of real estate taxes, as well as four months of expected maintenance costs and potential brokerage fees for expiring leases, in an escrow account to insure the investment.

“This is a deal that is in many ways exceptional,” a commercial broker who leads the capital market team at Studley, Woody Heller, said. “It will be a record price per square foot and a huge boost for market. It will set other records, too.”

Mr. Macklowe is selling the building to be able to pay off loans for that came due last month for a portfolio of seven buildings he bought last year for $7 billion. Last week, he made a deal with Deutsche Bank and a group of subordinate lenders to pay off a $5.8 billion loan by selling some of the properties. He is aiming to settle a $1.2 billion loan, which has accrued another $200 million in interest, with the Fortress Investment Group with the proceeds from the General Motors building sale.