Such companies shall, on or before March 1, make a return, under oath, to the commissioner, showing the gross premiums in force on risks in this state on December 31 previous and the unabsorbed portion of such premiums computed at the rate of return actually made on annual policies expiring during the year by said companies.
RSA 405:9
1913, 90:1. PL 275 :8. 1929, 13:1. RL 325:9.