Over the next few weeks, you might spot a letter marked "IMPORTANT voting information" for the 2019 Federal Election that looks official, and contains a postal vote application form asking for personal details. But they're not from the AEC.

The unbranded envelopes have been landing in people's mailboxes for the past few weeks, and contain a reply-paid envelope along with the form.

A number of recipients have told the ABC they thought it was an official letter from the Australian Electoral Commission (AEC), until they opened it to find campaign material inside.

The AEC has warned if you choose to fill out these forms and mail them in the supplied envelopes, they will not be sent directly to the AEC.

Instead, they'll be sent to your local candidate, who may open your application before forwarding it to the AEC for processing.

Both the Liberals and Labor are deploying them — the ABC has seen them in at least five states so far.

It sounds a bit sneaky, so Phil Arntzen from Western Australia asked the ABC's You Ask, We Answer project to investigate:

"How is it allowed that candidates can send out postal vote forms to return to them, which could be privacy-breached, and not direct to the AEC?"

The simple answer is:

According to the Commonwealth Electoral Act — which sets out all the rules for elections in Australia — political parties are allowed to distribute postal vote applications to electors, along with reply-paid envelopes addressed back to them.

"This is a longstanding provision of the electoral act," the AEC's director of media and issues management, Phil Diak, said.

But voters aren't required to apply or to use the envelope supplied if they do.

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"The applicant may instead choose to send a completed party-supplied postal vote application direct to the AEC," Mr Diak said.

"If it does go back to the party, it must be promptly onforwarded to the AEC. We then send the ballot papers and there's no further dealings with the party."

So why do political parties send them out?

Political parties spruik postal votes as an easy and convenient way to vote if you can't make it to a polling booth on election day.

But there is speculation data could be added to parties' internal databases, which they use to target you in the lead-up to the election.

Knowing how old you are, your full name, and even your security question could give a local candidate useful insight into who's living at that address, before they knock on your door.

They'll know what to bring up, or send you campaign material that's tailored to your interests, in a bid to capture your vote.

The ABC asked both the Liberal and Labor parties:

What happens if people post their application in the reply paid envelope provided by your candidates?

What happens if people post their application in the reply paid envelope provided by your candidates? Is the party transferring or recording that data on another system, before sending the application on to the AEC?

Is the party transferring or recording that data on another system, before sending the application on to the AEC? What data is being recorded?

What data is being recorded? What is that data then being used for?

What is that data then being used for? What provisions do you have in place to keep that data secure?



A spokeswoman for the Coalition party's HQ wrote back:

The party provides applications for postal votes to the AEC. All personal information is handled according to the legislative requirements required by the Privacy Act.

The Labor party did not respond before the ABC's deadline.

The postal vote application pack sent through to a voter in the seat of Boothby. ( Supplied )

Is it legal for parties to check out what's on the form?

Yep. Mr Diak said there was nothing stopping political parties from "extracting and viewing" your postal vote application, if it's sent back to them in the envelope they supplied.

That means they could access your:

Full name

Full name Date of birth

Date of birth Enrolled address

Enrolled address Postal address

Postal address Contact details (including your email address, mobile phone number and home phone number)

Contact details (including your email address, mobile phone number and home phone number) A security question and answer

Both Labour and the Liberals have sent postal vote forms to electors. ( Supplied )

What's that security question about?

When you apply for a postal vote, the AEC asks you to provide a security question and answer, which it will then use to verify your vote.

"When you receive your postal vote you'll be asked to write your answer on the envelope containing your ballot papers," the form states.

But that might not be information you want to divulge to political parties, with your only options including:

In what town/city were you born?

In what town/city were you born? What company did you first work for?

What company did you first work for? What was the last school you attended?

What was the last school you attended? What was the make/model of your first car?

What was the make/model of your first car? What is the middle name of your oldest child?

"Regarding the question of privacy, this is a matter for the applicant to consider in sending an application to a party," Mr Diak said.