Build a payment-evidence chain for every flip project

A flip project needs a payment-evidence chain whenever a dollar leaves the bank: link the property, the supplier document, the payment evidence, and the bookkeeping record. The bank line alone shows movement of cash; it rarely identifies the scope, project, or whether supporting documents are complete.

Use four linked records

Keep these references together under one property ID:

1. Business purpose. The property address or internal project ID, vendor, and a short description of the work or materials.
2. Supplier support. The estimate, invoice, receipt, credit memo, or other document that explains the charge.
3. Payment proof. The ACH confirmation, cleared check, card statement, or bank transaction reference.
4. Bookkeeping reference. The vendor bill, expense, or other approved accounting entry and the job or property reference used.

The IRS identifies invoices, receipts, deposit slips, paid bills, and payment records as supporting business documents.¹ This is an operational filing method, not tax or legal advice.

Work the chain before close

Do not ask the bookkeeper to infer a project from the vendor name. If a document covers more than one property, preserve the original document and add a written allocation approved by the person responsible for the project. If the bank payment differs from the invoice, leave an open question rather than forcing the two to agree.

Illustrative example. A $4,850 ACH payment to a roofer clears on June 18. The packet includes the final invoice, the ACH confirmation, Project FL-427, and the reference to the recorded vendor bill. The invoice contains a $350 materials credit that was applied before payment. The review note states that the cash payment is $4,850 and explains why it does not match the original $5,200 proposal. A future reviewer can follow the difference without recreating the story from a bank feed.

A handoff checklist

Before a payment enters the monthly close packet, confirm:

• the property or project identifier is present;
• the source document and payment evidence are linked;
• any difference from the estimate, invoice, or bank line has an explanation;
• one person owns unresolved questions; and
• the original files remain available when a vendor credit or final bill arrives later.

Use this chain beside the weekly property cost snapshot and the final-bills checklist for a sold flip. It supports project-level bookkeeping without deciding tax treatment, legal responsibility, or payment approval.