The strike action will affect helplines including the HMRC employer helpline, construction industry scheme (CIS), the student loans unit, PAYE registrations, maternity, paternity and sick pay.

The strikes are scheduled for 18 days with further action planned on 15-19, 22-26, 29-31 May and on 1 and 2 June.

HMRC strikers were out on the picket lines demanding a pay increase to reflect their skills.

The PSC union said the strike had been called to pressure the government to improve pay, pensions, job security and redundancy terms. The first strikes began last November and hit Budget day.

PCS pickets lined the road at the entrance to HMRC Benton Park View in Newcastle earlier this week on the first of 17 days of targeted strike action by members in personal taxation (PT) operations.

PCS national president Fran Heathcote spoke to the pickets at an early morning rally and thanked them for taking the action on behalf of all members.

PCS vice president Kevin McHugh, who works at Benton Park View also spoke at the rally, and regional TUC secretary Liz Blackshaw spoke to bring solidarity from the wider trade union movement. There was support from Prospect and solidarity from the FBU and CWU.

PCS member Chloe paused from giving out strike leaflets to say: ‘It’s so important we support this strike. With the cost of living so high pay needs to increase so staff can pay their bills. We deserve an increase that reflects the skills required to do the job, which helps to keep this country running.’

Up in Scotland, at the HMRC site at East Kilbride, there was also a well-supported picket line with around 12 members on picket duty this morning.

Holly added: ‘We want fair pay for all members. For my colleagues who are using foodbanks and those who had to choose between heating their home and putting food on the table. We were praised through Covid as key workers, but we have nothing to show for it. That’s why I’m on strike.’