Property Transaction Data vs Listing Data Transaction data describes completed/registered deals, while listing data describes asking offers. Listings can be withdrawn, duplicated, stale or negotiated below the advertised price, so the two datasets answer different questions.
Transaction data is usually better evidence of realized price but can arrive with delay and may cover only recorded variables; listing data can signal current supply and seller expectations earlier but carries selection and duplication bias. Never merge listing and transaction observations into one average without labeling the source and stage.
Compare like with like by date, location, property type and size, and report the gap between asking and realized evidence when both exist.
Valuation validity and property identity
Keep inspection date, report date, methodology and comparables, legal versus actual area, restrictions and assumptions distinct, and never let one valuation figure replace title, zoning or building-status checks. A valuation report should not be used outside its purpose, date and property identity. For each fact use a source capable of proving it and link the result to its effect on purchase, ownership or cost. Match the taşınmaz number, ada/parsel, independent-unit number and description to the transaction, and confirm the valuer is authorised within the SPK framework when such authorisation is required.
TKGM states that valuation reports issued before 9 December 2024 had a three-month validity window, while a Tutar Tespit Belgesi issued after that date has a six-month validity period; material changes to the property or application can also require a fresh valuation. The key is not merely that a signature or advertisement exists, but that the person acting had the legal capacity and authority for that act, on that date and within that scope. TCMB housing price indices provide market-movement context, not the value of one unit. Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition.
From market data to testable cash flow
Any rent-growth, resale-price or interest-rate assumption should be stress-tested with alternative scenarios rather than accepted as a single forecast. Property investment analysis must separate market data from the calculation for the specific asset. For each fact use a source capable of proving it and link the result to its effect on purchase, ownership or cost. TCMB publishes the House Price Index to track housing-market price movements and, in 2026, began publishing the New Tenant Rent Index to capture new-rental price developments more quickly than rent measures that include existing contracts.
These indices do not provide the sale price or rent of one unit, so they must be combined with verifiable local comparables. The key is not merely that a signature or advertisement exists, but that the person acting had the legal capacity and authority for that act, on that date and within that scope. Calculate gross yield from annual rent relative to price, then calculate net yield after vacancy, management, maintenance, insurance, taxes, dues and non-recoverable costs. For a capitalization rate, use NOI before debt service and distinguish property performance from leveraged equity return. Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition.
Property identity and the current registry
Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition. Web Tapu allows applications for transactions such as sale, mortgage and inheritance transfer, but it does not make an earlier registry copy current evidence. If a representative acts, check the representation document against the party’s identity, scope of authority and transaction type. A mismatch in unit, share, owner or a newly added restriction requires the file to be reconciled again before payment or completion.
The current TKGM land-registry record is the starting point for proving the owner and the property; an old title-deed copy or an advertisement is not a substitute. The key is not merely that a signature or advertisement exists, but that the person acting had the legal capacity and authority for that act, on that date and within that scope. Match the name and identity or legal-entity details, province, district, neighbourhood, ada/parsel and the independent-unit number where applicable. Read mortgages, attachments, annotations, easements and other restrictions before a material commitment. For each fact use a source capable of proving it and link the result to its effect on purchase, ownership or cost.