Stockton Council is writing to people across the Borough who need to renew their absent vote entitlement.
As part of important security measures all postal and proxy voters must provide a fresh signature specimen every five years.
Everyone who is required to submit a fresh signature will receive a new application for next week and will have until Monday, 12 March to return it in the pre-paid envelope provided. If documentation is not received by that date, they will have to re-apply or cast their vote in person at a polling station.
There is also the option to indicate if they no longer wish to vote by postal vote.
More than 31,000 people currently hold an absent vote and around 11,300 of those will be contacted to provide a fresh signature.
Councillor David Harrington, Stockton Council's Cabinet Member for Corporate Management and Finance, said: "We will be contacting everyone who has held an absent vote application for more than five years and it is vital they return a fresh signature by the deadline if they wish to continue to use a postal vote in any forthcoming elections.
"We have to send a reminder application form to everyone who does not reply before Wednesday, 15 February. I would encourage everyone to return it before this date to help us save extra printing and postage costs."