Table B.1: Adjusting 2014/15, 2015/16 and 2016/17 FRS levels of income and expenditure to 2018/19 and 2023/24Income source Updating factorFactor SourceEmployment income, self-employment incomeAverage weekly earnings indexONS financial year (March-April) annual average K54U; extrapolated beyond available statistics using OBR earnings forecast Table 3.5Non-simulated benefits (disability, carer’s and maternity benefits) and Basic State Retirement pension Change in main rate of benefitEarnings-related pension income (state, occupational and personal) "Triple lock" and CPIMortgage interest paymentChange in the mortgage interest rate (annual average)Bank of England IUMTLMV; extrapolated assuming moves with trend (2 years)Rent paid or receivedRent element of CPIONS; extrapolated to 2018 using same method as for earningsChildcare expenditureAs employment income Maintenance paid or receivedAs employment income Other private transfers...