The warning follows a dip in applications in 2020, indicating many are waiting until they are permitted to travel later this year.
The Home Office said that during the pandemic, the Passport Office saw a drop in the number of people applying for passports from around seven million to just over four million in 2020.
Passport Office director general Abi Tierney said: “It is vital those who may need to apply for a new passport do so now.
"If you have delayed renewing your passport or are applying for the first time, please apply now so you can receive it in good time.”
Text messages are being sent to those with passports nearing expiry.
