You will need documents that independently establish what the business actually does and earns, because the seller’s word is not evidence. Filed tax returns, bank statements, signed customer contracts, payroll records and a lease are the usual substitutes for accounts that were never properly kept.
Reconstruct the business from third-party records
The application has to answer two document-driven questions: whether the enterprise is real and operating, and whether it can produce more than a minimal living. Hypothetical example: the buyer of an American upholstery workroom is given handwritten turnover figures by a retiring owner and no formal statements at all; what rescues the file is the set of records neither party controls — three years of filed returns, twelve months of bank deposits, the supplier accounts, the payroll register showing four employees, and the signed lease on the premises. Ask for those in the purchase agreement as a condition rather than requesting them politely afterwards.
Where a gap remains, close it forward rather than backward: a forecast built on the customer contracts that are actually assignable, with a staffing schedule and dates, is more credible than a reconstruction of a past nobody documented. And keep your own side clean, because the file must also show where your capital came from and that it moved when you say it did.