Fitch Ratings is to introduce new indices to cover payment rates of claims submitted to lenders' mortgage insurance providers (LMI) across prime residential mortgage-backed securities.Fitch said this extra information is needed as losses that are not paid by the LMI may affect the transaction and RMBS investors."Generally, seven per cent to nine per cent of Australian prime RMBS losses are not paid by LMI," Fitch said in a media release.According to Fitch, to the end of March 2014, mortgage insurers paid 93.5 per cent of the cumulative submitted claims across all outstanding Fitch-rated Australian prime RMBS. Additionally, at least two per cent of realised losses are not submitted by the lender to the mortgage insurer, as they are not covered by the LMI policy (for example, damage to the security or penalty interest).In addition, the loans in default have averaged $80,000 to $90,000 over several years so, at seven to nine per cent, the losses are not large in absolute terms. Fitch said none of the Australian prime RMBS transactions that it rates have suffered a loss as a result of claim reductions in the 14 years to March 2014.