National Statistical Institute

Consumer Prices, Housing prices and PPP Department

2 Panayot Volov Str. 1038 Sofia

Bulgaria

The OOHPI is based on the ‘net acquisitions’ approach, which measures changes in prices paid by households for the acquisition of dwellings that are new to the household sector and changes in other costs related to the ownership, and transfer of ownership, of dwellings.

The OOHPI is broken down into the following expenditure categories:

• O.1. Owner-occupiers’ housing expenditure;
  • O.1.1. Acquisitions of dwellings;
    • O.1.1.1. New dwellings;
      • O.1.1.1.1. Purchases of newly built dwellings;
      • O.1.1.1.2. Self-build dwellings and major renovations;
    • O.1.1.2. Existing dwellings new to households;
    • O.1.1.3. Other services related to the acquisition of dwellings;
  • O.1.2. Ownership of dwellings;
    • O.1.2.1. Major repairs and maintenance;
    • O.1.2.2. Insurance connected with dwellings;
    • O.1.2.3. Other services related to ownership of dwellings.

Households which are owner occupiers.

The main statistical variables are price indices.

The basic unit of statistical observation are transaction prices of dwellings new to the household sector and of other products that the households acquire in their role as owner-occupiers.

Expenditures of private domestic and non-domestic households for the acquisition of newly build or new for the households’ sector dwellings on the territory of the country, or for the services that individuals had to pay as owner-occupiers of residential properties.

OOHPI covers the territory of the entire country. No regional indices are calculated.

OOHPI are available since 2010. Nevertheless experimental pilot OOHPI are available since the last quarter of year 2008.

2015=100

The following units are used:

- Index point;
- Percentage change on the same period of the previous year (rates);
- Percentage change on the previous period (rates);
- Percentage share of the total (weights).

OOHPI is a quarterly statistics.

EU legal acts:

• The basic act providing for the compilation of the OOHPI is the European Parliament and Council Regulation (EU) 2016/792, of 11 May 2016 on harmonised indices of consumer prices and the house price index, and repealing Council Regulation (EC) No 2494/95.
• The relevant implementing act is the Commission Implementing Regulation (EU) 2023/1470 of 17 July 2023 laying down the methodological and technical specifications in accordance with Regulation (EU) 2016/792 of the European Parliament and of the Council as regards the house price index and the owner-occupied housing price index, and amending Commission Regulation (EU) 2020/1148.

All relevant regulations as well as further methodological details can be found in the Housing Price Statistics section on Eurostat’s website under => Legislation.

Bulgarian legal acts and other agreements:

• Law on Statistics (Statistics Act);
• Annual National Statistical Programme;
• Strategy for Development of the National Statistical System, 2021 - 2027.

Not applicable for OOHPI.

Regulation (EC) No 223/2009 of the European Parliament and of the Council, of 11 March 2009, on the transmission of data subject to statistical confidentiality to the Statistical Office of the European Communities;

Statistics Act | National statistical institute (nsi.bg)

The confidentiality of the HPI data set is treated in respect of national legislation: Law of Statistics, Chapter 6 ‘Protection of secrecy’, Articles 25, 26, 26a, 27 and 27a. Art. 25 stipulates that individual data (‘individual data’ are data about a specific statistical unit) received and collected through statistical surveys shall constitute a statistical secret and may be used only for statistical purposes. Individual data received for the purposes of statistical surveys may not be used as evidence before the bodies of the executive and the judiciary.

The NSI and statistical authorities and their staff may not disclose or provide:

• individual statistical data;
• statistical data, which can be matched in a way that enables the identification of a specific statistical unit;
• statistical information, which aggregates data about less than three statistical units or about a population in which the relative share of the value of a surveyed parameter of a single unit exceeds 85 per cent of the total value of such parameter for all units in the population.

The individual data may be provided only if:

• it is transferred to Eurostat where this is necessary for development and production of European statistical information;
• it is provided to the National Statistical Institute by statistical authorities where this is necessary for development and production of official statistical information;
• the subject to which such data relate has granted consent therefor.

Individual anonymous data is provided for the purposes of scientific research to higher schools or legal entities, whose main activity is scientific research, with a permission of the Chairperson of the National Statistical Institute.

According to the Law of statistics the receipt, processing, usage and storage of statistical data representing statistical secret is carried out in a procedure set out in a regulation endorsed by the President of the National Statistical Institute.

The Section 3 of the Rules for Dissemination of Statistical Products and Services endorsed by the President of the NSI regulate the protection of secrecy of individual data.

The Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes endorsed by the President of the NSI regulate the relations in terms of provision of anonymised individual data by the NSI for scientific and research purposes and the order of their  receipt by the users.

Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes | National statistical institute (nsi.bg)

Data are treated in respect of national legislation: Individual data are not published in accordance with article 25 of the Law on Statistics. The publishing of individual data can be performed only in accordance with article 26 of the same law.

Statistics Act | National statistical institute (nsi.bg)

Specific rules for treating the data set with regard to statistical confidentiality are applied according to the Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes endorsed by the President of the NSI.

Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes | National statistical institute (nsi.bg)

In case of data anonymisation, the following requirements are applied:

• Anonymized data are separate statistical records which have been amended according to the best existing practices in order to reduce the risk of direct or indirect identification of the statistical units to which they refer
• Additional data processing means deletion of names, addresses, identification numbers and all of the characteristics that might lead to a risk of disclosure and misuse of individual records in the databases with individual data. Measures such as suppression of geographical details, age, place of birth, occupation, economic activity, type of ownership, etc. that can be taken in order to ensure that the identification of individuals and economic entities shall be impossible.
• Anonymised individual data cannot be provided if it is in conflict with the provisions of art. 25 of the Statistics Act;
• The individual records in the databases of the requested survey shall be processed by competent employees as all identifying individual attributes (name, address, publicly accessible identification number etc.) which directly or indirectly a given statistical unit can be identified shall be deleted from the data through.

In case of records in which some of the characteristics do not fulfilled these rules, the directorates responsible for the preparation of the data shall decide whether they should be completely deleted or to delete the data only in the cells of these characteristics or to take other appropriate solutions for protection of individual data.

The release of the Bulgarian OOHPI follows a preannounced official Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute.

The Release Calendar is publicly accessible on NSI’s website.

The calendar is available on the NSI website:

Release Calendar | National statistical institute (nsi.bg)

OOHPI are published on the NSI website, in section Housing price statistics in accordance with the Law on Statistics and the European Statistics Code of Practice respecting the professional independence and aimed at objectivity, transparency and equal treatment of all consumers.

Quarterly (OOHPI) and annually (weights)

Not available.

OOHPI table data are available on NSI’s website, theme Housing price statistics: Housing price statistics | National statistical institute (nsi.bg)

On-line database on NSI’s website, Information System INFOSTAT:

https://infostat.nsi.bg/infostat/pages/module.jsf?x_2=186

In principle, there is no access to microdata. The microdata, as long as it is not confidential, could be provided to users on request without a breach of the confidentiality principle.

Not relevant.

The OOHPI metadata is available on NSI’s website:

Owner occupied housing price index (OOHPI) | National statistical institute (nsi.bg)

The OOHPI Quality Reports is available on NSI’s internet site:

Owner occupied housing price index (OOHPI) | National statistical institute (nsi.bg)

All data are checked for completeness and consistency with statistical concepts and definitions. OOHPI are produced in compliance with OOH methodological requirements of the Owner-Occupied Technical Manual.

Automatic quality controls have been implemented within the production process in order to detect and correct errors. Outliers are excluded from calculations.

The OOHPI Quality Reports following the ESS Standard for Quality Reports Structure (ESQRS) are produced and are updated each year.

The OOHPI Quality Reports is available on NSI’s internet site:

Owner occupied housing price index (OOHPI) | National statistical institute (nsi.bg)

The main national users could be classified as follows:

• National state institutions: National Assembly of The Republic of Bulgaria, the Government, Bulgarian National Bank, national and state agencies. That group of users is considered as most important.
• Other national users: research communities, students, business communities, media, etc.
• Internal users: other statistical divisions in the NSI.

NSI conducts an annual online statistical survey "Users' satisfaction" which covers all statistical domains. It aims to assess user satisfaction in NSI data provision and to outline the recommendations for future development of statistical system according to the needs of the users.

Analysis of the last survey conducted in 2022 are available on the following link: User satisfaction

OOH sub-index 'O.1.1.2 Existing dwellings new to households' is still excluded from index calculation due to insufficient number of transactions.

The series for the sub-index 'O.1.1.1.2. Self-build dwellings and major renovations' currently are not compiled.

The sub-index for 'O.1.2.2 Insurance connected with dwellings' is not compiled due to the low share (under the threshold) in households' expenditures.

Statistical data are with good accuracy. The accuracy of OOHPI is assured by strictly following Eurostat's methodological recommendations and regulations.

There is a variety of data sources both for weights (NA data, Property Register, construction statistics, annual reporting of the enterprises, statistics on housing fund, etc.) and prices (administrative data, survey data, construction companies, real estate agents, municipalities, etc.) for compilation of OOHPI sub-indices. In cases where surveys are used the type of survey and the price collection methods are designed to ensure sufficient coverage and timeliness.

Sampling error is not calculated for the OOHPI sub-indices and for OOHPI as a whole.

Non-sampling errors are not quantified for the OOHPI. NSI tries to reduce non-sampling errors through continuous methodological improvements, survey process improvements and validation methods, which can help us to avoid coding and typing errors. 

The time lag between the end of the quarter to which the OOHPIs relate and their national publication is usually 82-85 calendar days.

Data are sent according to Regulation 2016/792: 85 days after the end of the reference period (indexes) and no later than June 15^th of the year following the reference year (weights).

Not relevant. The OOHPI regional data are not produced.

Since first quarter of 2015 until fourth quarter of 2021 OOHPI are fully comparable over time.

Due to transition towards administrative data source for calculation of “Purchase of new dwellings”, a break in time series should be considered in the first quarter of 2022.

Not applicable. There is only one set of OOHPIs available.

The OOHPI partly overlaps the scope of the HPI. However, both indexes cover a different set of transactions and any comparison of the two indices should be done with this in mind.

OOHPI are internally coherent. Higher level aggregations are derived from detailed indices in accordance with strictly defined procedures.

According to the budget estimates of the National Statistical Programme for 2022, the total cost of HPI, HIS and OOHPI production is 867.202 thousand euros.

The OOHPI series, including back data, is revisable under the terms set in Articles 27-29 of Commission Implementing Regulation (EU) 2023/1470.

No revisions to report.

See below.

The Bulgarian OOHPI price data is based on the following multiple data sources:

• Administrative data;
• Survey data.

The Purchases of newly built dwellings sub-index is compiled using the administrative sources:

• Property register (PR), maintained by the Registry Agency; and
• Cadastral Administrative-Information System (CAIS) by the Geodesy, cartography and cadastre Agency.

The Other services related to the acquisition of dwellings and the Other services related to ownership of dwellings sub-indices are compiled using the data from multiple data sources – administrative data and survey data.

The Major repairs and maintenance sub-index is based on survey data for producer prices in major repairs and maintenance of dwellings and residential buildings produced by Short-term Business Statistics and Transport Statistics Department of NSI.

The use of National Accounts data complemented with combined information from the Property Register (PR) and the Cadastral Administrative-Information System (CAIS) are used as main sources for derivation of OOHPI weights.

Quarterly, except for the Other services related to ownership of dwellings sub-index for which data is collected annually.

Data are collected from administrative data sources, by questionnaires or via Internet.

Purchases of new dwellings

The compilation is based on the combined information from the Property Register (PR), maintained by the Registry Agency (RA) and the Cadastral Administrative-Information System (CAIS) by the Geodesy, Cartography and Cadastre Agency data:

• PR data are collected monthly trough a web application for automated secure connection between NSI and the Registry Agency;
• Cadastral data are provided quarterly, in txt-files, using a safe data transmission channel.

Other services related to the acquisition of dwellings

The following information is collected from administrative data, from the survey on real estates’ fees and via Internet:

• Notary deeds – two component’s Tariff for notary fees to the Law on Notaries and Notarial Activity. The prices are collected via Internet. The central office of NSI is responsible both for data collection and for index calculation.
• Real estate fees – rates based on the results from the quarterly survey on the real estate fees. It addresses a sample of real estate agencies (NACE 68.31) with a significant share on real estate’s market. The Regional Statistical Offices (RSO) of NSI are responsible for data collection. The central office of NSI is responsible for index calculation.
• Registry Agency fees – average rate calculated from the administrative data on transactions combined information from PR and CAIS. The prices are collected via Internet. The central office of NSI is responsible for index calculation.
• Municipality (local) taxes – municipality taxes (flat rates) defined each year by the local authorities. The central office of NSI is responsible both for price collection and for index calculation.

Major repair and maintenance

Data are based on the survey ‘Producer prices in major repairs and maintenance of dwellings and residential buildings’ conducted by Short-term Business Statistics and Transport Statistics Department of NSI. The Regional Statistical Offices (RSO) of NSI are responsible for data collection. The central office of NSI is responsible for index calculation.

Other services related to ownership of dwellings

This component includes the cost of 'annual property tax' which is derived by a flat rate (in thousands) applied to the tax valuation of a property for each individual dwelling and is defined each year by local tax authority according the Local Taxes and Fees Act. The Regional Statistical Offices (RSO) of NSI are responsible for data collection. The central office of NSI is responsible for index calculation.

Administrative data

Validations include rules for automatic quality controls of prices and property’s area. They are done on two stages:

• annually - the price limits (minimum and maximum price level) in each strata are calculated based on the transactions from the previous year;
• quarterly- automatic check control are carried including determination of:

-        extreme values of prices by strata;

-        extreme values of area - below 20 sq.m and above 250 sq.m (for apartments) or above 350 sq.m (for single-family house).

Extreme values are identified and eliminated.

Variables available in both registers (RA and CAIS) pass through pre-defined validation rules during the merging process in order to investigate and remove incorrect interpretation of properties’ characteristics.

Survey data

First validation is done when data are received. There is no automatic rejection of records, each problematic record is considered individually and any necessary modifications are made only based on relevant information.

Major repair and maintenance

Automatic quality controls have also been implemented in the Information System used for “Producer prices in major repairs and maintenance of dwellings and residential buildings” calculation. When recording the data, the Information system “Business cycles” carries out obligatory and recommended controls according to set with validation rules. In case there are errors, the system displays a warning dialog error in the report. The system does not allow completion of the report until these errors have been corrected.

Data editing is carried out at the level of specification prices, if quarterly price movements (compare to the previous quarter) are outside the range of -15% to + 15% the electronic system automatically warns the responsible expert and these movements must be especially conformed by the enterprises with explanations.

See below.

See below.

OOHPI is a Laspeyres-type price index.

Purchases of newlybuilt dwellings

Aggregation steps from bottom up:

1. level 5 - locality by stratum (district centre, towns and rural, resorts);
2. level 4 - locality by NUTS level 3 (districts);
3. level 3 - locality by NUTS level 2 (statistical regions);
4. level 2 - locality by NUTS level 1 (statistical zones);
5. level 1 - newly built dwellings.

Other services related to the acquisition of dwellings / Other services related to ownership of dwellings

Aggregation steps from bottom up:

1. Calculation of geometric or arithmetic mean prices
2. Calculation of the elementary aggregates’ indices as ration of geometric or arithmetic prices.
3. Calculation of the higher level indices as weighted average of the low level indices with corresponding weights.

Major repair and maintenance

Aggregation steps from bottom up:

1. Calculation of total prices by specifications, as a sum of the price of materials and the price of labour
2. Calculation of geometric mean prices

2.   Calculation of the elementary aggregates’ indices of typical activities on major repair and maintenance as ration of geometric mean prices.

3.         Calculation of the higher level indices as weighted average of the low level indices with corresponding weights.

OOHPI sub-indices and elementary aggregates weights are based on data on National Accounts (NA) data complemented with combined information from the Property Register (PR) and the Cadastral Administrative-Information System (CAIS). National Accounts elaborate the necessary estimates on the base of comparison of the different data sources: dwellings capital stocks, their consumption of fixed capital, data for completed dwellings, annual report on revenue and expenditure of enterprises, report on revenues of construction enterprises by type of construction activities.

OOHPI weights for index calculations in year (t) reflect the average annual value of households' expenditures calculated from the preceding three years: (t-3), (t-2) and (t-1), price updated to the fourth quarter of (t-1).

OOHPI weights are updated annually.

Purchases of newly built dwellings

The NA data in combination with Property Register (PR) data and Cadastral Administrative-Information System (CAIS) are the sources that are used for derivation of the sub-index weights. Detailed weights are constructed using the information from the PR and CAIS.

Other services related to the acquisition of dwellings

The sub-index weights is estimated using the average rates of the corresponding services and the expenditure on purchases of dwellings derived from PR and CAIS.

Other services related to ownership of dwellings

The sub-index weights are based on NA data derived from Consolidated Fiscal Program (Ministry of finance) and estimates based on the average rates of the corresponding services and the expenditure on purchases of dwellings derived from PR and CAIS.

Major repairs and maintenance

The use of National Accounts (NA) data (average of the last three years, price updated to fourth quarter of t-1) in combination with data from annual reporting of enterprises are used for derivation of Major repair & maintenance weights. At highest level of aggregation NA, use data from HBS complemented with expert estimation. No distinction between major renovations and major repairs and maintenance is done.

On the detailed level, the annual reporting of enterprises is used. Enterprises from the sample have to report the amount of receipt of sales from the different maintenance and major repairs of own occupied dwelling and houses. This information is used to construct the weights for calculation the total price index.

OOHPI weights for index calculations in year (t) reflect the average annual value of households' expenditures calculated from the preceding three years: (t-3), (t-2) and (t-1), price updated to the fourth quarter of (t-1).

Purchases of newly built dwellings

Other services related to the acquisition of dwellings

Other services related to ownership of dwellings

Each year indices are calculated using fourth quarter of the previous year=100 as base reference period and are rebased to 2015=100 using the chain linked method.

Major repairs and maintenance

Each year indices are calculated using 2015=100 as base reference period.

See below.

Transaction prices are recorded after the transfer of the ownership, when the legal act is entered into the Property register.

VAT is included in the price of newly built dwellings.

Taxes other than VAT are not included in the price of dwellings.

Government subsidies are set up in the law on the settlement of the rights of citizens with multi-annual housing deposits. Deposits are derived from 'points', which are calculated by an initial amount of money placed on bank deposit by a citizen, and the number of years passed until a dwelling is purchased. In such cases dwelling are purchased at market prices and the deposit is refunded to the person after the transaction.

Hence, those transactions are covered by OOHPI in full transaction price, and the subsidies are not reflected. Other form of subsidies are dwellings sold by municipalities to households in need. Prices are set up in the ordinance issued by each municipality. Those dwellings are treated as 'existing dwellings new to households' sector' but due to their limited number of transactions index for 'O.1.1.2. Existing dwellings new to households' is not calculated and this component is not included in OOHPI.

The price of land is included in prices.

The price of land is excluded in weights.

Housing cooperatives are not covered in the OOHPI.

‘Non-market’ transactions are identified by the type of the registration act entered in the Property Register. ‘Non-market’ transactions are excluded from calculations.

The multi-object transactions are treated as one transaction if included properties belong to the same settlement.

The fractional transactions are treated as separate transaction.

See below.

Other services related to the acquisition of dwellings

Other services related to the ownership of dwellings

For compilation of price indices for elementary aggregates, the ratio of geometric mean or arithmetic mean prices is used.

Major repairs and maintenance

For compilation of price indices for elementary aggregates, the ratio of geometric mean or arithmetic mean prices is used.

Other services related to the acquisition of dwellings

Other services related to the ownership of dwellings

When replacing a product-offer by a new one, the following rules is applied:

• To choose another product with the most similar quality that belongs to the same EA/stratum and the one that accounts for the substantial amount of sales value in the outlet; and,
• To ask for the price of the new replacement product in the previous month.

When replacing an outlet/enterprise, price collectors are told to choose a new one, which has to be:

• of the same type;
• as similar as possible to the old outlet in term of their sales values.

Major repairs and maintenance

When a specific product subject to price monitoring, stop producing, is replaced with a new product in the same product group/enterprise, which will replace approximately the oldest product on the market (similarity of the quality).

Other services related to the acquisition of dwellings

Other services related to the ownership of dwellings

The prices are tariffs and the traditional tariff method of matched pairs is used.

Major repairs and maintenance

The replacement rules ensure that there is no difference between a replaced product and its replacement in terms of their specifications and the direct comparison is used.

Other services related to the acquisition of dwellings (real estate fees)

The main reasons for failing to collect some prices is temporally non-availability of the product-offers on the market and missing reports (non-response).

Prices for temporarily missing products are handled by one of following methods: (1) asking the enterprise to estimate the missing price, (2) imputing the missing price by the price change for the prices that are available from the same enterprise (3) imputing the missing price by the price change for a particular comparable product from similar enterprise, and (4) imputing the missing price by the price change for the prices that are available in the elementary aggregates.

Major repairs and maintenance

The main reasons for failing to collect some prices is temporally non-availability of the product-offers on the market and missing reports (non-response).

Prices for temporarily missing products are handled by one of following methods: (1) asking the enterprise to estimate the missing price, (2) imputing the missing price by the price change for the prices that are available from the same enterprise (3) imputing the missing price by the price change for a particular comparable product from similar enterprise, and (4) imputing the missing price by the price change for the prices that are available in the elementary aggregates.

Generally, the discounts and inducements are taken into account in the index if they are:

- applied to a specific product (an individual good and service);

- claimed at the time of purchase.

No cases where a product related to the acquisition or the ownership of dwellings is made available free of charge and a price is subsequently charged.

No cases where a product is made available for a price and is subsequently made available for free.

Where the VAT is applicable, it is included in the observed prices.

No seasonal adjustment is made.

None.