Don't get hung up on the concept of "Start-up" - what's relevant is the GAR. For any business it's the actual gross revenues you relied upon when making your credit decision. For start-ups that almost always is going to be zero unless you have financial statements for part of the fiscal year for the business.
If the situation involves a corporation and a change in ownership - the borrower remains the same, the corporation. So you would use whatever historical financial data for the corporation you relied upon. It would not be a start-up.
On the other hand if a business sold its assets to a new business that was started up to acquire the assets of the original business and you lend to the new business, that would be a new business entity with no financial history, a start-up situation and you would rely upon any actual historical financial information you have for that new entity to determine the GAR. If the new corporation has just been formed and you are lending to it and there is no historical financial data, the GAR would be "0".
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