(a) The surplus line broker shall remit to the Commissioner, on or before the fifteenth day of April, July, October, and January, at the time his or her quarterly affidavit is submitted, as a tax imposed for the privilege of doing business as a surplus line broker in this state, a tax of 4 percent on all premiums paid to the surplus line broker during the preceding quarter, less return premiums and exclusive of sums collected to cover state or federal taxes, on surplus line insurance subject to tax transacted by him or her during the preceding quarter as shown by his or her affidavit filed with the Commissioner.

(b) If a surplus line policy covers risks or exposures only partially in this state, the tax so payable shall be computed on the proportion of the premium which is properly allocable to the risks or exposures located in this state.