(a) Every insurance carrier shall pay a tax upon all workers' compensation or employer's liability premiums received in this State or on account of business done in this State at the rate of 2% of the amount of such premiums, which tax shall be in lieu of all other taxes on such premiums.
(b) The insurance carrier shall be credited with all canceled or returned premiums actually refunded during the year on such insurance and premiums on reinsurance received from other insurance carriers, except that mutual insurance companies shall be taxed upon the gross premiums charged and collected and shall not be credited with unabsorbed premiums or dividends.
(c) The taxes imposed by this section shall be collected as provided in § 702(d) and (f) of this title.