Tax office staff throughout Sussex will be taking industrial action tomorrow after rejecting a pay offer.
Workers will leave their offices an hour early at 4pm and will refuse to work overtime.
More than 900 Inland Revenue staff are expected to take part in the industrial action across Sussex.
Staff at the Brighton tax office in Regent Hill will be given home-made biscuits tomorrow with "4pm" iced on the top to remind them of the protest.
The action is being organised by the Public and Commercial Services Union which represents more than 50,000 Inland Revenue staff nationally.
David Quinn, PCS branch secretary, said: "We put forward our original request in April and it has taken until October for them to get back to us.
"They've made it clear they will not improve the offer through negotiation so the only option left to use was to take industrial action."
A further protest is planned for Wednesday.
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