TY JOUR TI VALUE ADDED TAX REFORM AND ITS IMPACT ON THE BUSINESS ENVIRONMENT IN RUSSIA KW Value Added Tax KW VAT KW VAT payers KW simplified taxation system KW VAT rates KW VAT reform KW business environment JO Russian Journal of Management AU Minakov, A.V. AU Suglobov, A.E. PY 2026 IS 14 PB Publishing Center RIOR