Evidence-based negotiation
How to negotiate a property asking price using public evidence
Most offers are a percentage. Ten per cent under, five per cent under, asking price because the market feels hot. A percentage is a feeling. An evidenced offer is a number you can explain, defend and hold — and agents respond very differently to the two.
Why evidence beats percentages
An estate agent's job is to get the best price for the seller, and their first instinct with a low offer is to test whether you will move. If your number came from a feeling, you will move, and both of you know it. If your number came from four registered sales, a floor area check and a quantified repair, there is nothing to test — the agent has to take it to the seller with the reasoning attached.
This also protects you from the opposite error: paying over the odds because the market is busy. Evidence tells you where the ceiling is, which is the number that actually matters.
Step 1 — gather the evidence
- Registered sold prices for the postcode and street from HM Land Registry Price Paid data. Completed transactions, not asking prices. See what sold data really tells you.
- Floor area from the EPC register, converted and compared to the listing. See square footage versus floor plan claims.
- Price per square foot for the property and for its comparables. See using £/sq ft variance.
- Condition and running-cost evidence from the EPC recommendations and any survey.
- Risk and constraint evidence — flood designations, planning refusals, conservation area restrictions.
- Market temperature — how long the listing has been up and whether the asking price has been reduced. See asking price drop history.
Step 2 — grade it before you use it
Split every item into evidence about this property and evidence about this area. Area evidence sets context; only property-level evidence should move your number. A postcode median tells you the neighbourhood; it does not tell you what the house with the failing roof is worth.
The rule FirstBid applies
Only high-confidence, property-level evidence is allowed to adjust a financial figure. Everything else is context, printed as context. Apply the same rule by hand and your offers get harder to dismiss.
Step 3 — build three numbers, not one
| Number | What it is | Where it comes from |
|---|---|---|
| Opening offer | Your evidenced starting position — credible, not insulting | Comparable-derived value less fully quantified deductions |
| Realistic target | Where you expect to land after two or three rounds | Comparable-derived value less the deductions you can prove |
| Ceiling | The number above which you walk away | Your affordability limit and the point where the evidence stops supporting the price |
Work all three out before you speak to the agent, and write the ceiling down. The full method is in opening offer, target and ceiling.
Step 4 — present it properly
- Make the offer by phone, then confirm it in writing the same day.
- Lead with your position as a buyer — chain-free, mortgage in principle, timescale — because certainty is worth real money to a seller.
- Give the evidence in three or four bullets, each with a source and a figure. Not a dossier.
- State the number once, and do not justify it twice.
- Say what you are flexible on that is not price: completion date, fixtures, survey timing.
There is a ready-to-adapt template in how to write an evidenced offer letter.
Mistakes that cost buyers money
- Using asking prices of unsold properties as comparables. They are advertisements, not evidence.
- Treating a postcode average as a valuation of a specific house.
- Deducting the full cost of every improvement you would like to make. Deduct what needs fixing, not what you would prefer.
- Revealing your ceiling. The agent's job includes finding it.
- Over-arguing. Once the evidence is on the table, silence does more work than repetition.
Nothing here is financial or legal advice, and no evidence pack guarantees a lower price — a motivated seller in a competitive market may simply say no. What evidence does reliably do is stop you overpaying without knowing it.
Frequently asked questions
- Do I have to show the agent my evidence?
- You do not have to, but summarising it makes the offer far harder to dismiss as a chancer's bid. Give the headline figures and sources, not your whole workings.
- Should I offer below asking on a property priced correctly?
- If the evidence supports the asking price, the honest answer is that your leverage is speed and certainty rather than price.
Sources
Check a property before you offer
Run any UK postcode through our free lookup for EPC bands, flood exposure, registered sold prices and recorded crime. Got a specific listing? Paste the Rightmove link for the full six-section FirstBid report.
Related guides
Using £ per square foot variance to justify a below-asking offer
How to calculate price per square foot from registered sold prices and EPC floor areas, choose fair comparables, and turn the variance into a defensible offer.
How to calculate your opening offer, realistic target and ceiling price
A repeatable way to set the three numbers every buyer needs before making an offer, built from registered sold prices and quantified property-specific costs.
What HM Land Registry sold data really tells you about local prices
How to read Price Paid data properly — what it includes, what it leaves out, the reporting lag, and how to use it as negotiation evidence without over-reading it.
How to write an evidenced offer letter to an estate agent
A free template for putting a property offer in writing with sourced evidence, plus what to include, what to leave out, and the wording that keeps the offer subject to survey.