Mrs Voss took over as head last September, weeks before a successful inspection allowed the 160-pupil school in the village of Walpole St Peter and St Andrew, Wisbech, Cambridgeshire, to be taken off the schools with serious weaknesses list.
At the time, she was confident that savings of about pound;25,000 would be enough to allow the school to continue its recovery.
Mrs Voss planned to replace her deputy head, who is due to leave later this year, and begin implementing reforms recommended by the inspectors. But she has since received her latest budget - pound;53,000 lower than in 20023.
She now fears that the school's hard-won gains will be wiped out.
Mrs Voss, who has seven teaching staff and an annual budget of pound;300,000, said: "The new budget has swallowed up our underspend and it will force us to put in place radical reductions. It is soul-destroying because I don't know how I can ask my staff to work any harder.
"I can't afford to replace my deputy, so his responsibilities will have to be shared around the teachers, and it will be impossible to implement the Government's plans for classroom assistants."
Like many heads, Mrs Voss said her budget was badly affected by the increase in pay, national insurance and pension costs. Changes in the Government's standards funding also meant the school lost its grant to curb infant class sizes.
"We have seven classes - one for each year. We knew we would have to cut the number of classes, but hoped to do it gradually. Now these cuts will be swift and harsh and not in the long-term interests of the school."