Evidence-based negotiation
How to calculate your opening offer, realistic target and ceiling price
Going into a negotiation with one number is how buyers get talked upward. Three numbers — an opening offer, a realistic target and a ceiling — turn the conversation into something you control.
Start with an evidence-derived range
Take the median £/sq ft of at least three genuine comparables from Land Registry Price Paid data, apply it to the verified floor area, and note the spread between your lowest and highest comparable. That spread is your honest uncertainty, and it should stay visible in your workings.
Then quantify deductions — carefully
| Deduct | Do not deduct |
|---|---|
| A quoted roof or damp repair | A kitchen you would replace by preference |
| A lease extension premium you have had estimated | General "it's a bit dated" |
| EPC-listed measures with contractor pricing | Modelled energy costs you have not verified |
| Regularisation or indemnity costs for missing consents | Risk you feel but cannot price |
One deduction, one source
Every deduction needs a document behind it: a quote, a register entry, a decision notice. If you cannot attach a source, it belongs in your ceiling calculation as caution, not in your offer as a line item.
Setting the three numbers
- Realistic target = comparable-derived value − fully evidenced deductions. This is the number you actually expect to agree, and the one to hold in your head.
- Opening offer = target less a modest, deliberate margin — enough to leave room for two rounds without being dismissed. On most UK sales that is a few per cent, not twenty.
- Ceiling = the lower of what your lender and budget allow, and the point at which the evidence no longer supports the price. Write it down before you start.
Then decide in advance what you will do if the seller counters above your ceiling. Deciding that in the moment, on the phone, is where budgets go.
Adjust for context, not for emotion
- Time on market and price reductions shift how much room there is — a listing reduced twice in four months is a different negotiation.
- Your buying position is worth real money: chain-free with a mortgage in principle can justify holding a lower number.
- Local market direction from the UK House Price Index for the local authority, not the national headline.
- Competing interest is asserted by the agent far more often than it exists. Treat it as unverified unless a formal best-and-final process is opened.
This is a negotiating framework, not financial advice. Your lender's valuation, your survey and your solicitor's findings all sit downstream of it and can legitimately change the number.
Frequently asked questions
- How far below asking should my opening offer be?
- There is no correct percentage. It should be your evidenced target less enough room for two rounds — derived from comparables, not from a rule of thumb.
- Should I tell the agent my maximum?
- No. In a best-and-final process you submit a single number, which is not the same as disclosing your ceiling in ordinary negotiation.
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
How to negotiate a property asking price using public evidence
A structured method for building an offer from registered sold prices, price per square foot, condition evidence and public records — instead of guessing a percentage off.
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 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.