Passport Office workers are walking out on strike for five weeks during peak holiday travel periods, in an escalation of a dispute over jobs, pay and conditions.
More than 1,000 staff are walking out between April 3 and May 5.
The Public and Commercial Services union, which represents passport workers, has warned the strike will have a “significant impact” on the delivery of passports as the summer approaches.
Holidaymakers planning summer travel are being urged to heed warnings about potential passport renewal delays triggered by the industrial action, which will take place over two Bank Holidays.
ITV News looks at how the strikes could impact those hoping to go on holiday this year.
What is the current process for renewing passports?
If your British passport has expired, you must renew it to travel abroad.
You must also renew it if you don't have enough time left on it (how much time you need on your passport depends on the country you're visiting).
It costs £82.50 to renew or replace your passport if you apply online, or £93 if you fill in a paper form.
Current guidance states you should allow up to 10 weeks for your passport to be processed.
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How will the strike impact someone wanting to renew their passport soon?
Although the Passport Office says it has contingency plans in place for the strike period, Lisa Francesca Nand from The Big Travel Podcast told ITV News the industrial action "probably will delay your passport if you need to renew it in the next few months."
Travel expert Simon Calder advises those planning to go on holiday over Easter, half-term in May or over the summer to check their passport now.
"See if it needs renewing," he said.
"But bear in mind the worst thing that could happen is that everyone panics and applies for their passport and that causes a bottleneck even before the strike has begun."
Will the strike affect renewal time?
Downing Street says there are "no current plans" to change the guidance that people should allow up to 10 weeks to get a passport.
A spokesperson said: "The Home Office will work hard to manage the impact of this strike action to ensure they can still provide the vital service to the British public as you would expect ahead of the summer."
What if my passport is currently being renewed? Will the strikes delay it?
Although the Passport Office warns that renewals could take up to 10 weeks, currently, the average processing time is much less, at around two weeks, Ms Nand said.
She added: "If your passport is currently being renewed, you will hopefully have it processed before the strikes begin in April.
"Lead times at the moment for passports are generally quite good."
Can I still fast-track my passport renewal?
Currently, the Passport Office operates a fast track service where you can pay £155 to get your passport renewed in one week.
The Passport Office has not yet said whether this service will operate over the five-week strike period.
"However, it is hoped that the fast track will still be available," Ms Nand said.
"Passports offices contingency plans will kick in to help this option still be available."