(1) The trust fund for a group including incorporated and individual unincorporated underwriters must consist of:

(a) For reinsurance ceded under reinsurance agreements with an inception, amendment or renewal date on or after January 1, 1993, funds in trust in an amount not less than the respective underwriters' several liabilities attributable to business ceded by United States domiciled ceding insurers to any underwriter of the group;

(b) For reinsurance ceded under reinsurance agreements with an inception date on or before December 31, 1992, and not amended or renewed after that date, notwithstanding the other provisions of WAC 284-13-500 through 284-13-590, funds in trust in an amount not less than the respective underwriters' several insurance and reinsurance liabilities attributable to business written in the United States; and

(c) In addition to these trusts, the group must maintain a trusteed surplus of which one hundred million dollars must be held jointly for the benefit of the United States domiciled insurers of any member of the group for all the years of account.

(2) The incorporated members of the group must not be engaged in any business other than underwriting as a member of the group and are subject to the same level of regulation and solvency control by the group's domiciliary regulator as are the unincorporated members. The group must, within ninety days after its financial statements are due to be filed with the group's domiciliary regulator, provide to the commissioner:

(a) An annual certification by the group's domiciliary regulator of the solvency of each underwriter member of the group; or

(b) If a certification is unavailable, a financial statement, prepared by independent public accountants, of each underwriter member of the group.