It is with a heavy heart, disappointment and determination that I will be striking on Wednesday. Disappointment, because I recognise the disruption this will cause. After a career spanning 34 years as a teacher and 21 as a Barnsley head, dedicated to improving the life chances of all children, to turn them away even for a day does not sit comfortably. It hurts.

Determination because the government has embarked on an illegitimate assault on our earned income which threatens the future of the education system and our profession. Like me, many head teachers are within 10 years of retirement so the impact is less should the proposals become reality. However I am acting on behalf of the next generation of teachers and, through them, children themselves.

We are told the system is broken and our pensions are unaffordable. So why has the government refused to conduct a formal valuation of the scheme that would prove it? We can only conclude that it would not support their case. Why is it that teachers have paid £46 billion more into the scheme than they have taken out?

Yes, we are living longer. In 2007 we voluntarily reformed our scheme to pay more and for teachers to take on the risk of longer life expectancy. We are not unreasonable! The reforms are working as confirmed by the Audit Office. The current proposals are not aimed at funding or securing public sector pensions - they are a cynical tax on teachers to reduce the deficit. We will do our bit in a financial crisis - we are already in the middle of a two year pay freeze saving hundreds of millions of pounds, and we pay taxes like everyone else - but the attack on our pensions goes too far. It seems to us cowardice to attack dedicated public servants while largely ignoring those who caused the crisis.

We have tried to negotiate and will continue to do so. If there is intransigence in the process, it rests with the Treasury, who have driven us to the brink with a curious mix of arrogance, misinformation and incompetence. I will make my stand on Wednesday with thousands of colleagues.

The first NAHT strike in the union's history must tell you something.

We apologise sincerely for the inconvenience, but it is one day for the country against damage that will last the rest of our lives.

Steve Iredale is vice-president of the National Association of Head Teachers and a Yorkshire head teacher