Save the Children UK is expecting to lose about £25m in income by the end of the year because of the coronavirus pandemic.
The charity said the fall in income was mainly because of the closure of its 125 shops and the cancellation of events and community fundraising activities.
It comes as Save releases its latest annual report, which shows the charity increased its overall income by £4.2m in 2019 to £307.4m.
The report says the coronavirus pandemic has had a “significant impact” on the organisation and it was adjusting financial plans and updating its 2019 to 2021 strategy to reflect the impact of the outbreak.
A spokesman for the charity said Save was planning on the basis that it could lose £25m of income by the end of the year.
The charity has furloughed about 200 of its 900 UK staff at various points since March and has put a temporary freeze on recruitment, pay and almost all of its variable external spending.
The pay of the charity’s executive directors, which was frozen at 2018 levels, have been reduced by 10 per cent until the end of the year.
But the spokesman said the charity had not made anybody redundant because of the crisis and there had been “no discernible change in monthly donations from our generous supporters in the UK”.
He said: “We are confident that the robust action we have taken will enable us to continue our vital work for the most vulnerable and marginalised children in the UK and more than 100 other countries.”
While Save's expected income reduction is significant, other major charities are predicting larger shortfalls.
Cancer Research UK is making about 500 roles redundant because of an expected £300m fall in income over the next three years, while Barnardo's, which has a similar annual income to Save, said income could fall by £50m this year.
Save's annual report shows that income from donations and legacies fell by £2.6m to £89.2m in 2019 but funds from charitable activities rose by £6.1m to reach £200.3m.
Save received £17m less from the government in 2019 than in the previous year after it temporarily withdrew from bids for new funding during a since completed Charity Commission inquiry into how the charity handled sexual harassment complaints against two former senior staff members.
But it received funding for various projects totalling £23m from the United Nations, the global fund Education Cannot Wait and the Disasters Emergency Committee.
Last year, the charity’s overall income fell by £103m because of the end of several long-running government-funded programmes and fewer major emergencies.
The latest report says the charity spent £846,852 on termination costs in 2019, which were “incurred primarily as a result of implementing new operating models for our programming, fundraising, advocacy and technology teams to improve delivery of our strategy”.
Save did not respond to a request for more details on these costs, but the accounts say the charity’s average full-time equivalent headcount fell from 1,110 in 2018 to 1,036 last year.
The charity supported 9.5 million children in 130 humanitarian emergencies over the course of 2019, the accounts say.