Members are being asked by the union to strike over a three-day rolled out action in various areas:
- Wednesday 30 July - North West England and Wales
- Thursday 31 July - Scotland and Midlands
- Friday 1 August - Northern (including Cumbria), Yorkshire & Humber, Eastern, London and South East, South West and Northern Ireland
*** UPDATE 30 July ***
In a statement HMRC said it is giving those who need to renew tax credits until 6 August to do so, due to the strike meaning some might find it hard getting through to the tax credits renewal helpline.
It encouraged users to use the new online renewal service in the meantime where possible, or post or self-serve over the phone using the automated speech-recognition service.
Tax credits customers with changes to declare must now tell HMRC by 6 August or they will lose their tax credits.
Lin Homer, chief executive of HMRC, said she was "disappointed" by the PCS' timing to strike.
"It is a great shame that the union is asking HMRC staff to strike, deliberately putting the livelihoods of hard-working families at risk to further an industrial dispute," she said.
The union said in a message to members that the leverage in striking at a busy time "for a department which is already papering over significant cracks is obvious".
The PCS wants to win concessions on various issues including staffing levels, job security, personnel policies, office closures and privatisation.
June strike action was hailed by the union as "highly successful and effective" as it says 2,500 permanent posts have been advertised. The PCS claimed the recruitment drive was a "direct result" of the action.
In addition to the planned strikes, the union has also asked members not to work overtime, as the money HMRC spends on this per month equates to 1,000 permanent roles.
"We owe it to those whose jobs are threatened not to let HMRC off the hook in terms of masking shortages in staffing. HMRC is in utter chaos due to the level of job cuts.
"The tax credits and self assessment peak at the end of July make the employer [HMRC] vulnerable. By taking rolling action over these three days, you can maximise the pressure and help achieve a breakthrough towards our legitimate demands," the union said.
HMRC PCS members have already taken strike action twice this year, in February and June