Tax avoidance practices through the manipulation of business expenses in tax returns (SPT) constitute a crucial issue in modern taxation systems, particularly with the implementation of the coretax system. Several cases in Indonesia and various court rulings demonstrate that business expense manipulations have been adjudicated as criminal acts. These include manipulation through management fee items, fictitious invoices used as tax-deductible expenses, inflated transfer pricing to affiliated companies, as well as expenses derived from sham transactions. The purpose of this research is to determine the legal enforcement against tax avoidance carried out by taxpayers by inflating business expenses in their tax returns. This study employs a normative legal research method. The results indicate that not all tax avoidance efforts conducted by taxpayers by means of inflating business expenses automatically constitute a criminal offense, provided that it is carried out in a lawful, complete, accurate, and clear manner, supported by legitimate and valid transaction evidence. Therefore, this research implies that not all tax avoidance actions involving the inflation of business expenses are invariably subject to tax criminal penalties, unless executed to the contrary or performed unlawfully and without valid and accurate transaction evidence.