Seven out of 10 Suffolk schools are getting less money per pupil than five years ago - with a total funding shortfall over £20million, it has been claimed.
These figures, provided by the National Education Union and the School Cuts Campaign, show the levels of change in per pupil funding across primary and secondary schools in the region.
Almost 75% of schools in Suffolk and north Essex have seen a drop in per pupil funding in the last five years.
Three Ipswich secondary schools - Chantry Academy, Ipswich Academy and Northgate High school - accounting for almost £1.5m alone.
Craig D'Cunha is the headteacher at Chantry Academy, the school with the largest annual shortfall in funding projected for 2020/2021. They are expected to be underfunded by £510,127.
Mr D'Cunha said: "We have to make savings where we can so we don't have to make cuts to the quality of education our students get.
"We have more students coming in than leaving, and we get funding on the basis the number of students leaving.
"This means we have less funding than we need this coming year, but we have a fantastic business manager at the school and we know there will be a year down the line where we have more leaving than joining, so we'll have more money for that year.
"I'm not saying it doesn't make things difficult, but it's a balancing act."
Six primary schools in Suffolk are receiving more than £1,000 less per student than they were five years ago. Yoxford and Peasenhall Primary Academy is the hardest hit, losing £4,281 per pupil.
Graeme White, spokesman for Suffolk for the NEU, said: "The school funding crisis has been ongoing for some years.
"The current government has promised some money but it' is too little, too late.
"Schools are having to make cutbacks to the number of teachers in the schools or the support staff that provide vital extra help to pupils - they are not getting that help now.
"Every child matters and every child deserves and education, but it seems the government thinks that some matter more than others. Second best is not good enough."
Across north Essex the picture is even more troubling, with no school seeing an increase in per pupil funding over £300.
The biggest drop in per pupil funding across Colchester, Tendring and Braintree is Great Tey CofE Primary School, receiving £1,603 less per pupil than they did five years ago.
The biggest annual shortfall in funding is at Clacton Coastal Academy, where it expected the school will be underfunded by £968,244.
Paul Whiteman, general secretary of the National Association of Head Teachers, said: "It is very clear that there will still be winners and losers.
"One in three schools will only receive an increase of around 1.8% in their overall funding, which is still a real-terms cut.
"This shows that it will take a lot more than the Government is currently offering in order to properly restore the funding that's been lost over the past several years."
What is happening at a national level?
In this election campaign all the major parties are promising to invest in education, with Boris Johnson's Conservatives promising to deliver £7.1bn per year on top of current funding for English schools by 2022-23.
Labour are offering to provide free school meals to primary school children and reduce class sizes.
The Liberal Democrats have one of the more ambitious pledges, promising 20,000 more teachers and more than £10b extra funding per year by 2024/25.
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