The Due-Diligence File for a Property Purchase

A property purchase produces a pile of documents in a few frantic weeks: title searches, surveys, enquiries and replies, certificates, draft contracts, finance offers. Most buyers keep whatever lands in their inbox. A proper due-diligence file is organised so that three questions can be answered years later: what did we know, when did we know it, and what did we rely on? The same file is what a buyer's adviser will ask for on the day you sell.

How to organise it

One file per property purchase, with sections that mirror the questions due diligence asks. The exact documents vary by country and property type, so check with your adviser what applies where you are, but the structure holds everywhere.

1. Title and ownership

• Title documents or registry extracts, with the date obtained
• Plans showing boundaries
• Easements, rights of way, restrictions and covenants
• Any mortgages, charges or liens registered against the property, and evidence they will be cleared

2. Physical condition

• Survey or inspection reports, including specialist reports such as structural, damp or drainage
• Photographs taken at viewing and inspection, dated
• Quotes obtained for defects found, which often support a price renegotiation

3. Legal and regulatory

• Planning and building permissions for the property and any alterations
• Completion certificates or sign-offs for works
• Local authority or municipal searches, and anything they reveal
• Safety and energy certificates required where you are. For rentals, see safety certificates and compliance records.

4. Enquiries and replies

Every question asked of the seller, and every answer, dated. This is the section people most regret not keeping. If an answer later turns out to be wrong, the written reply is your evidence of what you were told. Keep follow-up questions with the original, not in a separate thread.

5. If there are tenants

• Existing tenancy agreements and any variations
• Rent schedule and arrears position
• Deposits held and where they are protected, if that applies in your jurisdiction
• Correspondence about disputes, repairs or notices already served

6. Money

• Offer letter and agreed price, including any renegotiation
• Finance offer and conditions
• Completion statement showing every amount paid and received
• Tax and fee calculations and receipts

7. Contract and completion

• Drafts with the adviser's comments, and the final signed contract
• Completion date and evidence of transfer
• Post-completion registration confirmation

Naming and dating

Every document should say what it is and when it applied, in the filename or its description: 2025-06-14 Survey report - Main St 12.pdf tells you everything a scan0043.pdf does not. File naming conventions people actually follow has a scheme you can adopt.

After completion: turn it into the property record

The due-diligence file becomes the start of the property's permanent record. Certificates will have renewal dates; tenancies will have break and review dates; warranties expire. Pull those dates out into a list you actually check, or into a case-based system where each property is a record with the dates on it and the documents attached. If you own with others, agree up front who keeps the master copy; see co-owned property records.

How long to keep it

At least as long as you own the property, plus whatever period tax and limitation rules require after you sell. Title, permissions and completion documents are the ones a future buyer will ask for, so keep those in their original form.