Five of the nine insurers fined in December for failing to meet Motor Insurance Database (MID) targets are now compliant, according to the Motor Insurers' Information Centre (MIIC).
The insurers were issued fines of between £1,000 and £250,000 for failing to forward accurate information on 95% of their policyholders within 14 days of receipt.
Neil Drane, head of the MIIC, said: "It is very encouraging news and demonstrates that the fines we issued were enough to push the recipients into action."
The MIIC continues to refuse to reveal the names of the firms which did not meet the 31 October deadline.
Insurers were given six months to hit the targets, with fresh sanctions scheduled for April 2006. Drane said: "I am confident that the remaining non-compliant firms will be up to scratch by then."