How to write property buying criteria your whole firm can use

If every deal still lands on your desk, your buying criteria aren't written down. They're in your head. Property buying criteria are the rules that decide which deals you chase: where, what, the numbers a deal must hit, the refurb you'll take on and the exit that has to work.

Write each rule so two people would apply it the same way. Label it Stop, Flag or Prefer. Log one line on why you passed on every deal you turn down. Do that and the same document briefs your sourcers, trains your next hire and lets a system do the first pass. You keep the decision, and the same team gets more offers out.

What criteria in one head cost you

The usual sourcing brief is one line: BRRR, North West, under £150k, 20% ROI. Every phrase needs a phone call. Is the ROI on cash in, or after refinance? Which towns, and which streets in them? Is £150k the asking price or the all-in cost?

You know the answers. Your sourcer, your analyst and any software you point at that line do not. So they guess, deals arrive that miss, and you review every one yourself. That isn't carelessness. Give two people the same one-line brief and they will judge the same deal differently, and so will you on a Monday versus a Friday. Researchers call that variability "noise", and it shows up wherever judgement isn't written down.

Stop, Flag, Prefer: rules two people apply the same way

The test for every rule: if two people read it and look at the same deal, do they reach the same answer? If not, rewrite it.

Then give every rule one of three labels:

• Stop  The deal fails. Nobody needs to look at it.
• Flag  The deal goes to a person, with the reason attached.
• Prefer  Breaks a tie between two deals that both pass.

Next to each rule, write one line on why it exists. "No flats above the fourth floor" is a rule. "Because two lenders on our panel won't lend on them" is the reason. The reason lets your team handle the edge case, and tells you when to change the rule. The rules plus the reasons are your firm's written judgement: the one asset a competitor can't buy, however good their software.

What your criteria should cover

Six blocks. Each one answers a question you already ask of every deal.

The sourcer check deserves its Stop. HMRC lists property finders among the businesses that must register, and trading without registration is a criminal offence. In one 2024 analysis, 35 sourcing businesses were fined £150,299 in total for anti-money laundering breaches.

Copy this: a one-page buying criteria sheet

One strategy per sheet. Stops first, because that is the order a sourcer or a system will check them in.

Log why you passed

Criteria are half the asset. They say what you buy in general. The other half is what you decided on each deal, and why.

Your deal tracker says Passed, or Offer £118,000 accepted. It doesn't say you went £6,000 over your ceiling because the vendor needed a four-week completion and the contractor had already priced the refurb. Venture firm Foundation Capital calls these records decision traces: systems store the outcome, but the reasoning lives in people's heads and message threads, and leaves with them.

The fix is small. Add one column to your tracker: why. Fill it in for every pass, every purchase and every exception, in one sentence. Once a month, read the column. A reason that appears three times is a rule you haven't written down yet, so add it to the sheet.

Recorded reasons are what let a system take work off the founder. One ten-person software company that recorded its decisions for two years turned them into rules and built AI "judges" to apply them. In eight days, the founder reports, the judges decided 7,296 questions, sent 2,213 back and held 1,863 for a human. The founder stepped in 27 times. Their scale isn't yours. The principle is: a decision can only be delegated once its reasons are written down.

Test it on the deals you've already turned down

1. Pull your last 30 passes and your last 10 purchases.
2. Run each one through the sheet without looking at what you decided.
3. Where the sheet says yes and you said no, there's a rule you haven't written. Write it, with its reason.
4. Where the sheet says no and you bought anyway, either the rule is wrong or the deal was an exception. Decide which, and log it.
5. Give the same 10 deals to two people separately. Where they disagree, the rule is still vague.

Put it to work

Your sourcer brief. Send the sheet itself, Stops first. Then measure it: each month, track the share of each sourcer's deals that pass your Stops. A sourcer whose pass rate doesn't rise after they've had the sheet isn't reading it.

Your next acquisitions hire. They learn your judgement from the rules, the reasons and the log, instead of six months of shadowing you.

A first pass on every deal. Once every rule is testable, a system can check each inbound deal against the Stops, attach the Flags and send you only what's worth your time. It doesn't need a complex model. The hard part was always writing the rules down, which is why our method maps that step before anything gets built.

Common mistakes

• Numbers with no reason. A minimum yield nobody can explain gets ignored the first time a deal looks exciting.
• Everything is a Stop. If every rule is a must-have, the team treats none of them as one.
• One person's sheet. If two people decide on deals, both write their rules down and reconcile the differences. Expect some.
• Written once. Review it every quarter, and whenever the why column shows a new pattern.
• Living in a chat thread. One current version, in one place. Sourcers get that version only.

Frequently asked questions

What is a buy box in UK property investment?

A buy box, or buying box, is the set of written criteria a property investor uses to decide which deals to pursue: location, property type, price, minimum returns, refurb limits and exit. For a firm, it works best written as testable rules, each labelled Stop, Flag or Prefer, with a one-line reason next to it.

What should a property sourcing brief include?

Your Stops first: strategy, target postcode districts, property type and tenure, maximum all-in cost and minimum return with its formula written out. Then your Flags, then your Prefers. Before sharing deals or money, ask the sourcer for their HMRC anti-money laundering registration and redress scheme membership.

What is a deal decision log?

A deal decision log records one line on why each deal was passed on, bought, or bought as an exception to your rules. Your criteria say what you buy in general. The log records what you decided on each deal and why. Reviewing it monthly shows the rules you use but have not written down.

Can AI screen property deals against buying criteria?

Yes, if the criteria are written as testable rules. A system can check each inbound deal against your Stops and pass anything flagged to a person with the reason attached. If the rules are vague, AI applies them inconsistently, just as people do.