Unfortunately we are unable to publish an estimate of the weight that FISIM would have in our price indices. This is because we do not have a price index for FISIM that we can use to price update the lagged HHFCE expenditure and derive the current expenditure weight.
We have calculated a rough estimate of the weight that FISIM would have in CPIH, which was published in the APCP-T paper APCP-T(17)07 Including the cost of finance in CPIH and HCIs. For 2016 the weight (not price updated) was approximately 20 parts per thousand. FISIM expenditure can be found in the Consumer Trends release. Using the current price, not seasonally adjusted dataset you can see that FISIM is typically around 20 parts per thousand of total expenditure between 1997 and 2016. This would be higher in CPI, which does not include Council Tax or owner occupiers' housing costs.
The technical advisory panel have asked us to include FISIM as a low priority on our work programme, and we will investigate further when resource allows.