Alexová, M. (2016). Mineral oil tax gap (update). [Alexová, M. (2016). Daňová medzera na dani z minerálnych olejov (aktualizácia)]. IMF: Ministry of Finance of the Slovak Republic, Institute of Financial Policy (in Slovenian). Retrieved April 23, 2025 from https://www.mfsr.sk/sk/financie/institut-financnej-politiky/publikacie-ifp/manualy/danova-medzera-dani-z-mineralnych-olejov.html
ATI. (2024). About Addis Tax Initiative. Addis Tax Initiative (ATI). Retrieved December 20, 2024, from https://www.addistaxinitiative.net/about
ATO. (2024, December 24). Australian tax gaps – overview. Retrieved January 8, 2025, from Australian Taxation Office: https://www.ato.gov.au/about-ato/research-and-statistics/in-detail/tax-gap/australian-tax-gaps-overview/overview
Bitzenis, А., Vlachos, V. (2016). The legal framework for the shadow economy in the European Union. International Journal of Diplomacy and Economy, 3 (2). Retrieved December 5, 2024, from https://www.inderscienceonline.com/doi/abs/10.1504/IJDIPE.2016.081215
Breusch, T. (2016). Estimating the Underground Economy using MIMIC Models. Journal of Tax Administration (JOTA), 2 (1), 41-72. Retrieved January 5, 2025, from https://journals.docuracy.co.uk/jota/article/view/137
Chengelova, E. (2014). Shadow Economy in Perception of the Bulgarian Society. Economic and Social Alternatives, No. 3. [Ченгелова, Е. (2014). Икономиката в сянка в представите на българското общество. Икономически и социални алтернативи, No. 3]. (in Bulgarian). Retrieved April 20, 2025, from https://www.unwe.bg/uploads/Alternatives/1_br_3_2014.pdf
CRA. (2016). Tax Gap in Canada: A Conceptual Study. Canada Revenue Agency (CRA). Retrieved January 1, 2025, from https://publications.gc.ca/site/eng/9.838560/publication.html
CRA. (2022). Overall federal tax gap report: Estimates and key findings for non-compliance, tax years 2014-2018. Canada Revenue Agency. Retrieved January 4, 2025, from https://www.canada.ca/en/revenue-agency/corporate/about-canada-revenue-agency-cra/tax-canada-a-conceptual-study/tax-gap-brief-overview/overall-federal-tax-gap-report.html
CRA. (2023). Underground Economy Strategy 2022+. Canada Revenue Agency (CRA). Retrieved November 5, 2024, from https://www.canada.ca/en/revenue-agency/programs/about-canada-revenue-agency-cra/corporate-reports-information/underground-economy-strategy-2022.html
CRA. (2024). The Underground Economy in Canada, Sources and Methods. Canada Revenue Agency (CRA). Retrieved November 15, 2025, from The underground economy in Canada, sources and methods
DGTI. (2024, March). Revealing Gaps in the Tax Gap (Menguak Celah Dalam Tax Gap). Directorate General of Taxes of Indonesia (DGTI) – PAJAK. Retrieved January 28, 2025, from https://stats.pajak.go.id/id/artikel/menguak-celah-dalam-tax-gap
Dimitrova, V. (2024). Hidden Economy in Bulgaria Estimated by the MIMIC Approach Economic and Social Alternatives, 30 (4). [Димитрова, В. Скритата икономика в България, отчетена чрез MIMIC подхода. Икономически и социални алтернативи, 30 (4)] (in Bulgarian). doi:https://www.unwe.bg/doi/alternativi/2024.4/ISA.2024.4.03.pdf
Durán-Cabré, J. M., Moré, A. E.-M., Mas-Montserrat, M., Salvadori, L. (2019). The tax gap as a public management instrument: Аpplication to wealth taxes. Applied Economic Analysis, 27 (81). doi:https://www.emerald.com/insight/content/doi/10.1108/aea-09-2019-0028/full/html
EC, CASE, WIVO. (2024). VAT compliance gap due to Missing Trader IntraCommunity (MTIC) Fraud. Final report: phase 1. European Commission (EC), Center for Social and Economic Research (CASE), Austrian Institute of Economic Research, Vienna (WIVO). Retrieved May 5, 2025, from https://data.europa.eu/doi/10.2778/25011
EC, CASE. (2024). VAT Gap in the EU: 2024 Report. European Commission (EC), Center for Social and Economic Research (CASE). Retrieved January 12, 2025, from https://taxation-customs.ec.europa.eu/taxation/vat/fight-against-vat-fraud/vat-gap_en#reports-2009---2024
EC. (2021). European Semester Thematic Factsheet: Undeclared Work (Shadow Economy). European Commission. Retrieved December 29, 2024, from https://commission.europa.eu/system/files/2021-01/european-semester_thematic-factsheet_undeclared-work_en.pdf
Erard, B. E. (2023). Bottom-Up Estimation of the VAT Reporting Gap in Bulgaria (English). The World Bank. Retrieved June 22, 2025, from http://documents.worldbank.org/curated/en/099011224101530531
EY, EC. (2023). Report: Strengthening tax compliance by assessing external context and taxpayers’ behaviour – Empirical analysis of non-compliance in Bulgaria. Empirical analysis. European Commission (EC), Ernst & Young (EY). Retrieved January 20, 2025, from https://reform-support.ec.europa.eu/publications-0/strengthening-tax-compliance-assessing-external-context-and-taxpayers-behaviour_en
EY. (2025). Shadow economy: Estimates for the world and policy paths (Report). Ernst & Young (EY). Retrieved August 10, 2025, from https://www.ey.com/content/dam/ey-unified-site/ey-com/en-gl/insights/tax/documents/ey-gl-shadow-economy-report-02-2025.pdf
Feige, E. L. (2016). Reflections on the Meaning and Measurement of Unobserved Economies: What do we really know about the “Shadow Economy”? Journal of Tax Administration (JOTA), 2 (1).
FRS. (2019). Corporate Income Tax Gap 2015 to 2019. Federal Revenue Service of Brasil (FRSB) – Receita Federal. Retrieved January 15, 2025 from https://www.gov.br/receitafederal/pt-br/centrais-de-conteudo/publicacoes/estudos/tax-gap
FTA. (2023). Estimates on the Shadow economy and Tax gap. Finland tax administration. Retrieved January 8, 2025, from https://www.vero.fi/en/grey-economy-crime/scope/estimates-on-the-shadow-economy-and-tax-gap/
FTGPG, EC. (2016). The Concept of Tax Gaps, Report on VAT Gap Estimations. European Commission. Brussels: Fiscalis Tax Gap Project Group, European Commission. Retrieved December 27, 2024, from https://taxation-customs.ec.europa.eu/system/files/2016-09/tgpg_report_en.pdf
FTGPG, EC. (2018a). The Concept of Tax Gaps Report II: Corporate Income Tax Gap Estimation Methodologies. European Commission. Brussels: Fiscalis Tax Gap Project Group, European Commission. Retrieved December 27, 2024, from https://www.europarl.europa.eu/cmsdata/161065/Part%20II%20_%20Estimation%20Methodologies.pdf
FTGPG, EC. (2018b). The concept of Tax Gaps Report III: MTIC Fraud Gap estimation methodologies. Fiscalis Tax Gap Project Group, European Commission. Retrieved January 13, 2025, from https://taxation-customs.ec.europa.eu/system/files/2018-12/tax_gaps_report_mtic_fraud_gap_estimation_methodologies.pdf
Harremi, M. (2014). A simple analysis of the tax gap Balkan region. Mediterranean Journal of Social Sciences, Vol. 5, No. 19. Retrieved January 28, 2025, from https://d1wqtxts1xzle7.cloudfront.net/34658220/MJSS_August_2014_Vol.5_No.19_Content.pdf?1410144940=&response-content-disposition=inline%3B+filename%3DThe_Freedom_of_Choice_a_snob_or_a_gentle.pdf&Expires=1738019915&Signature=XQwevC7rr39fL-7kZkFrlTKR4oYZ5PF
HMRC. (2017). The Hidden Economy in Great Britain – Final report. Her Majesty's Revenue and Customs (HMRC). Retrieved November 15, 2025, from https://assets.publishing.service.gov.uk/media/5a74a49ae5274a56317a5f7f/P11533_HE_Final_report_MASTER_draft_v6_0_PC_FINAL.PDF
HMRC. (2021, December). The tax gap and compliance yield – what they are and how they relate. Retrieved January 8, 2015, from Her Majesty's Revenue and Customs of the United Kingdom (HMRC): https://www.gov.uk/government/publications/tax-gap-and-compliance-yield-technical-note/the-tax-gap-and-compliance-yield-what-they-are-and-how-they-relate
Hutton, E. (2017). The Revenue Administration – Gap Analysis Program: Model and Methodology for Value-Added Tax Gap Estimation. IMF. Retrieved January 2, 2025, from https://www.imf.org/en/Publications/TNM/Issues/2017/04/07/The-Revenue-AdministrationGap-Analysis-Program-Model-and-Methodology-for-Value-Added-Tax-Gap-44715
Hutton, E. (2023). E-training: RA-GAP VAT Gap Estimation Model (VGAPx), Module 1: Overview of the VAT Gap Modeling Framework. IMF. Retrieved April 8, 2024, from https://www.imf.org/en/Capacity-Development/Training/ICDTC/Courses/VGAPX
IMF. (2015). Current Challenges in Revenue Mobilization: Improving Tax Compliance. Washington, D.C.: International Monetary Fund. Retrieved January 2, 2025, from https://www.imf.org/en/Publications/TNM/Issues/2017/04/07/The-Revenue-AdministrationGap-Analysis-Program-Model-and-Methodology-for-Value-Added-Tax-Gap-44715
IMF. (2021). ISORA 2018: Understanding Revenue Administration. International Monetary Fund. Retrieved January 5, 2025, from https://www.imf.org/en/Publications/Departmental-Papers-Policy-Papers/Issues/2021/11/03/Understanding-Revenue-Administration-464865
IMF. (2021). The Revenue Administration Gap Analysis Program: An Analytical Framework for Personal Income Tax Gap Estimation. International Monetary Fund. Retrieved January 22, 2025, from https://www.imf.org/en/Publications/TNM/Issues/2021/08/27/The-Revenue-Administration-Gap-Analysis-Program-460749
IRS. (2005). Report: Your Federal Income Tax. Internal Revenue Service of the United States. Retrieved January 8, 2025, from https://www.irs.gov/pub/irs-prior/p17--2005.pdf
IRS. (2016). Tax gap estimates for tax years 2014–2016. The Internal Revenue Service (IRS) of the United States of America. Retrieved January 2, 2025, from https://www.irs.gov/newsroom/the-tax-gap
ISORA. (2024). International Survey on Revenue Administration (ISORA) – Periodic Data tables "Compliance Risk Management": Tax Gap 2021, 2022, 2023. International Survey on Revenue Administration (ISORA) – Multi-organisation survey of CIAT, IMF, IOTA, OECD and ADB. Retrieved April 23, 2025, from https://data.rafit.org/regular.aspx?key=74180916
Karpuzuva, M., Naydenov, A. (2024). The Shadow Sector of Bulgarian Economy: Assessments and Perceptions of Business. Economic and Social Alternatives, 4 (30). [Карпузова, М., Найденов, А. (2024). Сенчестият сектор на българската икономика: оценки и възприятия на бизнеса. Икономически и социални алтернативи, 4 (30)] (in Bulgarian). doi:https://www.unwe.bg/doi/alternativi/2024.4/ISA.2024.4.01.pdf
Khwaja, M. S., Iyer, I. (2014). Revenue Potential, Tax Space, and Tax Gap – A Comparative Analysis (Vol. WPS6868). The World Bank. Retrieved May 2, 2025, from https://documents1.worldbank.org/curated/en/733431468038088702/pdf/WPS6868.pdf
Korauš, A., Gombár, M. Vagaská, A., Šišulák, S., & Černák, F. (2021). Secondary Energy Sources and Their Optimization in the Context of the Tax Gap on Petrol and Diesel (in Slovakia). Energy Management: Economic, Social, and Ecological Aspects. Energies, 14 (14), 4121. doi:https://doi.org/10.3390/en14144121.
Kosova, T., Slobodyanyuk, N., Polzikova, H., & Šatanová, A. (2018). Tax Gap Management: Theory and Practice. Economic Annals-ХХI, 174 (11–12), 22–28. doi:https://doi.org/10.21003/ea.V174-04
Koufopoulou, P., Williams, C. (2019). Shadow Economy: Definitions, terms & theoretical considerations. Advances in Management & Applied Economics, 9 (5). Retrieved January 3, 2025, from https://www.scienpress.com/Upload/AMAE/Vol%209_5_3.pdf
Mark, J., Mazur, A. H. (2007). Understanding the Tax Gap. National Tax Journal, 60 (3). Retrieved January 1, 2025, from https://www.jstor.org/stable/41790406
MEF, Italy. (2016). Report on the unobserved economy and tax and social security evasion. [Relazione Sull`Economia Non Osservata e Sull’evasione Fiscale e contributiva] (Italian version). Ministero dell'Economia e delle Finanze, Italia (in Italian). Retrieved January 8, 2025, from https://www.mef.gov.it/ministero/commissioni/rel_ev/index.html
Mitu, N. E. (2023, Editura Universitaria Craiova). Can the Tax Gap be a Useful Tool in Terms of Tax Performance? Revista de Științe Politice (Revue des Sciences Politiques), 77, 20–28. Retrieved June 7, 2025, from https://www.ceeol.com/search/article-detail?id=1195044
NRA. (2025). NRA introduces new tools to measurement the impact of external context on non-compliance. Posoki, 75, 18–20. [НАП. (2025). НАП въвежда нови инструменти за измерване влиянието на външния контекст върху неспазването. Посоки, 75, 18–20] (in Bulgarian). Retrieved June 9, 2025.
OECD. (2012). Reducing opportunities for tax non-compliance in the underground economy. Organisation for Economic Co-operation and Development. Retrieved November 25, 2025, from https://www.oecd.org/en/publications/reducing-opportunities-for-tax-non-compliance-in-the-underground-economy_088ad0b9-en.html
OECD. (2016). Co-operative Tax Compliance: Building better tax control frameworks. Organisation for Economic Co-operation and Development. doi:https://doi.org/10.1787/9789264253384-en
OECD. (2017). Shining Light on the Shadow Economy: Opportunities and Threats. Organisation for Economic Co-operation and Development. Retrieved January 29, 2025, from https://www.oecd.org/content/dam/oecd/en/publications/reports/2017/09/shining-light-on-the-shadow-economy-opportunities-and-threats_a9a92285/e0a5771f-en.pdf
OECD. (2022). Consumption Tax Trends 2022: VAT/GST and Excise, Core Design Features and Trends. Organisation for Economic Co-operation and Development. Retrieved January 20, 2025, from https://www.oecd.org/en/publications/consumption-tax-trends-2022_6525a942-en.html
OECD. (2024). Tax Administration 2024: Comparative information on OECS and other Advanced and Enerming economics. Organisation for Economic Co-operation and Development. Retrieved December 29, 2024, from https://www.oecd.org/en/publications/tax-administration-2024_2d5fba9c-en.html
Patricio, B., Hutton, E. (2023). Corporate Income Tax Gap Estimation by using Bottom-Up Techniques in Selected Countries: Revenue Administration Gap Analysis Program. International Monetary Fund. doi:https://doi.org/10.5089/9798400246265.005
Petrova, E. (2022, November). Thoughts about tag gap, the tax compliance and efficiency of the tax system. Intra-European Organisation of Tax Administrations (IOTA). Retrieved January 5, 2025, from https://www.iota-tax.org/publications/iota-papers/thoughts-about-tax-gap-the-tax-compliance-and-efficiency-of-the-tax-system
Raczkowski, K. (2015). Measuring the tax gap in the European economy. Journal of Economics and Management, Vol. 21 (3). Retrieved January 28, 2025, from https://www.researchgate.net/publication/301803819_Measuring_the_Tax_Gap_in_the_European_Economy
Schneider, F., Buehn, A. (2010). Shadow Economies All over the World: New Estimates for 162 Countries from 1999 to 2007. The World Bank. Retrieved December 14, 2025, from https://documents.worldbank.org/en/publication/documents-reports/documentdetail/311991468037132740/shadow-economies-all-over-the-world-new-estimates-for-162-countries-from-1999-to-2007
Schneider, F., Raczkowski, K., Mróz, B. (2015). Shadow economy and tax evasion in the EU. Journal of Money Laundering Control, 18 (1), 34–51. doi:http://dx.doi.org/10.1108/JMLC-09-2014-0027
STA. (2008). Tax Gap Map for Sweden – How was it created and how can it be used? Swedish Tax Agency. Retrieved January 26, 2025, from https://www.skatteverket.se/download/18.361dc8c15312eff6fd2b9a4/1708608556405/Report_2008_1B.pdf#:~:text=During%202007%20the%20National%20Tax%20Agency%20has%20tried,between%20different%20areas%20and%20different%20groups%20of%20taxpayers.
STA. (2021). Tax gap report 2020: Background report for the annual report: the size and development of the tax gap. Swedish Tax Agency (Skatteverket). Retrieved January 11, 2025, from https://www.skatteverket.se/download/18.96cca41179bad4b1aa8c0b/1632316511065/Tax%20gap%20report%202020.pdf
TADAT. (2019). Subnational Supplement Field Guide. The Tax Administration Diagnostic Assessment Tool (TADAT). Retrieved January 25, 2025, from https://www.tadat.org/content/dam/tadat/en/assessments/TADAT%20Subnational%20Field%20Guide%20-%20November%202019.pdf
TADEUS. (2024). Overview 2024. Tax Administration EU Summit. Retrieved January 5, 2025, from https://taxation-customs.ec.europa.eu/taxation/tax-transparency-cooperation/tadeus_en#priorities
Thackray, M., Alexova, M. (n.d.). The Revenue Administration Gap Analysis Program: An Analytical Framework for Excise Gap Estimation. International Monetary Fund. Retrieved January 22, 2025, from https://www.imf.org/en/Publications/TNM/Issues/2017/04/20/An-Analytical-Framework-for-Excise-Duty-Gap-Estimation-Excise-Gaps-in-Tax-Administration-44720
Ueda Junji. (2018). Estimating the Corporate Income Tax Gap: The RA-GAP Methodology. International Monetary Fund. Retrieved January 22, 2025, from https://www.imf.org/en/Publications/TNM/Issues/2018/09/12/Estimating-the-Corporate-Income-Tax-Gap-The-RA-GAP-Methodology-45890
UNI-WIDER. (2024, December). Toolkit for the estimation of tax gaps using a bottom-up approach. doi:https://doi.org/10.35188/UNU-WIDER/WTN/2024-2
Yotov, Y. (2025а). Excise Tax Compliance Risk Management in Bulgaria: Limitations and Guidelines for Overcoming them. Economic Thought Journal, 70 (1), 97–127. [Йотов, Й. (2025). Управление на риска за спазване на акцизните задължения в България: ограничения и насоки за преодоляването им. Икономическа мисъл, 70 (1), 97–127] (in Bulgarian). doi:https://doi.org/10.56497/etj2570106
Yotov, Y. (2025b). Survey "Tax Compliance Risk Management and Some Excise Duty Issues", December 2024 – January 2025. Yonko Yotov, Google Forms. [Йотов, Й. (2025). Анкета „Управление на риска за спазване на данъчните задължения и някои въпроси за акциза“, декември 2024 – януари 2025. Йонко Йотов, Google Forms] (in Bulgarian). Retrieved June 20, 2025 from https://docs.google.com/forms/d/e/1FAIpQLSeTy_a53iWvxZdgZAeXJ3rkV2kE4A6YylhB4x0JEaLTwzHPbg/viewanalytics