Section 440.49(9), F.S., creates the Special Disability Trust Fund (SDTF) which is maintained by annual assessments, paid quarterly, by the insurance companies writing workers’ compensation insurance in the state, the commercial self-insurers, the assessable mutuals, and the self-insurers. Section 440.49(9), F.S., requires the Department to determine the rate each year for the next calendar year based on the statutory formula and such amount shall be prorated among the insurance companies writing compensation insurance in the state and the self-insurers. Section 440.51, F.S., provides for the maintenance of the Workers’ Compensation Administrative Trust Fund (WCAFT) by annual assessments, paid quarterly, upon the carriers writing compensation insurance in the State of Florida and self-insurers. The Department is required to notify, by July 1 of each year, carriers and self-insurers of the assessment rate, which shall be based on the anticipated expenses of the administration of Chapter 440, F.S., for the next calendar year. The total expenses of administration shall be prorated among the carriers writing compensation insurance in the State of Florida and self-insurers. Section 624.5094, F.S., provides that for purposes of calculating the annual assessments for the SDTF and WCAFT, any amount paid or credited as dividends or premium refunds in the same calendar year by the insurer to its policyholders must be deducted from “net premium,” “net premiums written,” “direct premium,” and “net premium collected” for the calendar year. Such offset for dividends or premium refunds paid or credited for the current year must be applied against the current year’s net premium for that year’s assessment regardless of the policy year for which the dividends or premiums are being reimbursed.