Signed client agreements or engagement letters, issued invoices and payments received, a business bank account in the company's name, registration and any required licence, insurance certificates, a lease or coworking agreement, and supplier or subcontractor contracts. Marketing material and a live website help, but transactional records carry the weight. Gather these in one file before the plan is drafted.
Keep company money out of personal accounts
Service founders often pay startup costs from a personal card and reimburse later, which makes the investment trail hard to read. Open the company account early, run every business payment through it, and keep a schedule linking each expenditure to a receipt and a purpose. Where a personal payment was unavoidable, document the reimbursement.
Clean separation also answers the source-of-funds question, since each business payment can then be traced back to identified personal capital. Add one document that service businesses can produce and that says more than a forecast: evidence that customers exist. Signed client agreements, a subscription or retainer schedule, deposits received, a booked calendar, or a supply arrangement with a business that will refer work — each is a fact rather than a projection, and a small number of them changes how the rest of the plan reads.
Keep them with the financial records rather than in a separate marketing folder. Hypothetical example: a founder opening a personal-training studio has three signed twelve-month client agreements and a corporate wellness arrangement, and those four documents carry more weight than the revenue forecast they support, because they are the only part of it that has already happened.