To ensure the smooth operation of the National Health Insurance system, the premium for the National Health Insurance is a compulsory one, making it a type of monetary payment under public laws, and it therefore is shared-payment by nature. According to Article 18 of the National Health Insurance Act, the premium payable by the insured and their dependents in Categories 1 through 4 referred to in Article 8 of the same Act shall be calculated according to the insured payroll-related amount and the premium rate of the insured. For the purpose of public interest, a State establishes various institutions and, to maintain functions thereof, requests payments from and to be shared by the beneficiaries. Beneficiaries contribute and share such payment to obtain the opportunity of receiving benefits payment from the State; they are not receivers who have already realized such benefits payment. Therefore, the principle behind receipt of the shared-payments by the State is for the purpose of attaining a balance between benefit and burden. As it is impossible to determine exactly the opportunity to receive the said benefits payment and its amount, the only way is by resorting to projected estimation. The premium paid by the insured to National Health Insurance is for potential receipt of benefits payment from the State, and is used for expenses to sustain operation of the National Health Insurance system. The premium rate for the National Health Insurance, therefore, should naturally be determined by actuarial study based on expected loss ratio. In principle, the balance between revenue and expenditure takes priority in considering the said premium rate. As benefits payment under the National Health Insurance shall be equal to the premium payable by the insured, making up for all expenditures regarding benefits payment by the State shall be fundamental. The said premium is not determined in proportion to potential benefits payments for the insured. The National Health Insurance is social insurance, and prescribes payroll-related premiums to achieve fairness in terms of cost-bearing capability. Given the vast dissimilarity between income and affordable premium among the insured subscribing to National Health Insurance, it is impossible to take into consideration the precise financial capability of all the insured. For the purpose of simplification, therefore, the insured payroll-related amount applicable is reasonably calculated according to the category of the insured. Accordingly, Article 21, Paragraph 1, of the National Health Insurance Act authorizes the competent authority to set, as a calculation base of premium to be contributed by the insured, a grading table for the insured payroll-related amount applicable. Article 22, Paragraph 1, Subparagraph 3, and Paragraph 3 of the same Act provide that, for independently practicing professionals and technicians to subscribe to the said insurance, the insured payroll-related amount applicable shall be determined by income from professional practices and subject to examination by the insurer, which may make adjustment at its own discretion if the insured payroll-related amount is found inappropriate. Accordingly, Article 41, Paragraph 1, Subparagraph 4, of the Enforcement Rules of the National Health Insurance Act stipulates: "The person in charge of a business employing more than twenty insured, and accountants, lawyers, architects, doctors, dentists, and Chinese medical doctors who are practicing independently may subscribe to coverage according to the highest level of the Insured Amount Grading Table; provided those whose income does not reach the highest level of the Table may subscribe according to the amount claimed with proof but not be lower than the highest level of the Insured Salary Grading Table of Labor Insurance." The legislative intention is to estimate the relevant expenditure requirement according to functions of the National Health Insurance, actualize premium rates, and set various insured payroll-related amounts applicable. The aforesaid is based on the statute and takes into consideration the occupation type of the insured, and therefore conforms to the intention of the parent law authorization and does not contradict the Constitution regarding the purpose of property right protection.