Scope the question Market data is useful only when its source, date
Scope the question Market data is useful only when its source, date, geography and method are known. Do not mix asking prices with transaction prices, means with medians, or a national index with a single-property valuation.
Core controls Define the sample before calculating: same micro-market, property type, age, size, floor and condition where possible; separate asking from transaction data and disclose outlier handling and adjustments. What official sources say TURKSTAT states that house-sales statistics are published monthly at national, provincial and district levels using TKGM/TAKBİS transaction records, with breakdowns such as first/second-hand and mortgaged/other sales.
Use transaction volume as an activity signal, not as a price per square metre. TCMB introduced the New Tenant Rent Index as an indicator of current price developments in the rental housing market for newly contracted rents, using housing valuation-report data.
Valuation validity and property identity
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. Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition. TCMB housing price indices provide market-movement context, not the value of one unit. 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. 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. An error here can change who has possession rights, the valid security/deposit position, eviction risk, or net income after dispute and costs. For each fact use a source capable of proving it and link the result to its effect on purchase, ownership or cost.
From market data to testable cash flow
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 each fact use a source capable of proving it and link the result to its effect on purchase, ownership or cost. For a capitalization rate, use NOI before debt service and distinguish property performance from leveraged equity return. Any rent-growth, resale-price or interest-rate assumption should be stress-tested with alternative scenarios rather than accepted as a single forecast. Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition. Read this evidence together with the “From market data to testable cash flow” review before relying on the conclusion.
Property investment analysis must separate market data from the calculation for the specific asset. 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. An error here can change who has possession rights, the valid security/deposit position, eviction risk, or net income after dispute and costs. Turn the review topic into provable facts: identity, date, amount, registry status, document or technical condition.