About 300 post offices may have to reduce or cancel services across the festive period, after a trade union confirmed that strike action will take place – make sure you send your parcels before Monday 19 December to avoid extra hassle.

The Communication Workers Union (CWU) has announced that thousands of Post Office counter staff will take part in industrial action between Monday 19 and Saturday 24 December following disputes over job security and workers' pensions.

The Post Office has claimed that 97% of its 11,600 branches will not be affected by the strike and that all Royal Mail postal services will continue as normal.

However, a total of 300 branches will be affected by the strike action in the form of reduced or cancelled services (fewer than 100 branches are expected to close entirely) – meaning customers in certain parts of the country may experience difficulties sending parcels during the six-day period.

The CWU claims that although only a small percentage of post offices will be impacted by its strike, the affected branches account for a high proportion of transactions and that other local post offices that are set to remain open could come under additional strain.

Confirmation of the strike action coincides with an announcement by union Unite that delivery drivers at Argos will also be on strike on 20 December due to disagreements over pay.

How will I be affected by the Post Office strike?

Around 3,000 Post Office counter staff are expected to go on strike, but those who are actually delivering mail will continue to work as normal – so most postal deliveries will be made within the usual timeframe.

But if you've a parcel that needs delivering, this may be where it gets a tad more complicated.

Counter staff are often responsible for processing the delivery of parcels, so if you don't manage to send your parcel before next Monday (19 December), you should check the Post Office's website or its social media channels to find a branch near you that is open and able to provide you with the service you require.

How can I be sure my delivery makes it to its destination by Christmas Day?

Royal Mail has confirmed that the strike will not impact its ability to make deliveries, so provided you're able to send your items, they should reach their destination within the usual time.

The pre-Christmas postal deadlines are not affected and are as follows:

  • Special delivery Saturday guaranteed – Friday 23 December
  • Special delivery guaranteed – Thursday 22 December
  • UK First Class and First Class Signed For – Wednesday 21 December
  • UK Second Class and Second Class Signed For – Tuesday 20 December

Will I still be able to collect travel money from the Post Office?

If you were supposed to be collecting travel money between 19 and 24 December, but your allocated branch is closed or operating a reduced service, the Post Office will be able to offer advice on picking up your money from an alternative branch.

What's caused this strike action?

The upcoming Christmas strike is the latest example of industrial action taken by the CWU over plans to restructure the Post Office network and the impact this will have on job security. In April, the Post Office announced plans to transfer up to 60 branches into WHSmith stores to cut costs.

Kevin Gilliland, Post Office group network and sales director, said he was "disappointed" with the CWU's decision to announce the strike ahead of the two sides discussing concerns.

He said: "We're extremely disappointed that [the CWU] prefers to call for strike action, particularly at such a critical time of year. This can only cause concern for our customers and our people. We want to reassure customers that if strike action takes place next week at least 97% of our 11,600 branches will not be involved. Our priority will be to support them.

"We have robust contingencies that will ensure that all branches have the support and cash they need to operate. Experience tells us we can manage this effectively and minimise the impact on the communities who rely on our services. Any action will affect fewer than 300 of our branches, and many of these will be open to maintain services for customers preparing for Christmas.

"It will be business as usual in almost all of our network, with over 50,000 Post Office people on hand to support customers as they make their preparations for Christmas."

However, CWU assistant secretary Andrew Furey said: "The union invited the Post Office to a week of talks, where we could sit down every day and come to an agreement. They have only offered to talk with us for one day.

"This dispute has been going on for months and can't be resolved in one day. The last time we negotiated with the Post Office, at the ACAS offices, was 5 October. We've had three strikes since then and they still haven't gotten round the table to negotiate."