Jeff Salway: One small change that will make a huge difference to millions of us

What seems at first glance a trivial technical change will in fact affect us all over the coming years - and not in a good way. Yet awareness of the move, and therefore the backlash it deserves, is almost non-existent.

The government's sly switch of inflation benchmark could prove one of its most enduring and painful financial legacies. Yet the nature of the change means many people remain completely in the dark as to what is happening and how it affects them.

The consumer price index (CPI) gambit reared its head again in last week's Budget. The Chancellor announced that the annual rise in several allowance thresholds will in future be linked to the CPI measure of inflation and not the retail price index (RPI), the current benchmark - CPI was 4.4 per cent in February, the most recent data, and the RPI was 5.5 per cent; significantly higher.

What this means is that from next April, the annual increase in the allowances for individual savings accounts (Isas), capital gains tax (CGT) and national insurance contributions (NI) will be lower. The inheritance tax (IHT) threshold will be CPI linked from 2015.

Having last year announced the same switch in the annual uprating of benefits and pensions and not experienced the backlash it may have expected, the government is playing with its new toy for as long as it can.

CPI is to replace RPI in calculating changes to state and public sector pensions; state benefits (including housing and incapacity benefits and jobseeker's allowance); CGT, IHT, NI and Isa allowances; the Pension Protection Fund and the Financial Assistance Scheme, among others.

This will hurt millions - savers and investors, pensioners, low-income families, public sector workers (including the armed forces), the disabled, the unemployed and members of failed pension schemes.

A pensioner receiving 10,000 a year from their final salary pension will be more than 800 a year worse off by 2016 because of the switch to CPI, according to consultant Towers Watson.

The government argues that because CPI doesn't include mortgage payments it better reflects the rate of inflation facing pensioners.

Campaigners disagree, not least the Royal Statistical Society, which said CPI doesn't constitute a "good measure of price inflation as experienced by households to be used in uprating pensions and benefits".

It is stealth taxation that for many people will, long term, make the government's other austerity measures seem trivial.

The latest banking complaints figures are out today and Scotland's taxpayer-backed banks will feature heavily. Their response to the Financial Services Authority data will highlight the proportion of complaints relative to their customer base.

That would be a good point to refer back to the numbers that really matter - the proportion of complaints found in favour of the customer.This data is published by the Financial Ombudsman Service and it revealed earlier this month that more than half of complaints in the second half of 2010 were upheld in favour of the consumer, including 74 per cent of Lloyds TSB complaints.

Antonio Horta-Osorio, the new head of Lloyds Banking Group, wants to reduce the overall number of complaints it receives by 20 per cent in the first half of this year.

Commendable - but how many complaints it receives is not the main issue. How it handles those complaints is the biggest indicator of how seriously it takes its customers. Lloyds has a long way to go on that front.