Can I vote in the Labour leadership contest? And how much will it cost?

Labour is undertaking its second leadership contest in a year, after the party's National Executive Committee (NEC) awarded Jeremy Corbyn an automatic ballot position on Tuesday. His leadership is to be challenged by two previously supportive MPs that were once in his shadow cabinet: Angela Eagle and Owen Smith.

If the NEC's decision wasn't dramatic enough, last-minute changes to the contest's rules have sparked anger among many supporters.

In theory, all party members, registered supporters and members of Labour affiliated groups can vote. Membership starts at £47 for a yearly standard membership, while registered support costs £25.

However, a six month membership freeze and alterations to what "registered support" means have left many potential voters ineligible. If you're unsure about whether you will be able to participate then here are all the key questions answered:

Yes, as long as you joined before 12 January 2016.

After last night’s announcement on the new rules, there was some confusion as to whether members who joined since 12 January could still vote by becoming registered supporters. It seems that this is the case.

If you joined the party since January and wish to vote for its leadership then you will have to also join as a registered supporter for £25. Full details of how to register are expected to be released on Thursday, although it has already been confirmed that the window for registration will be open for two days next week: 18 Monday - 20 Wednesday July.

Just like all other recent members, yes, if you are willing to pay. Labour has gained more than 130,000 voters since last month’s vote to leave the EU. However, since the vote fell after the membership freeze date of 12 January, all post-Brexit members are ineligible to vote.

Some who have joined since January are claiming that this decision could mean that Labour are in contention with Trading Standards laws, amid claims of being misled – on the sign up page online it says that registered support allows all members to vote in elections.

For now at least, it seems that all members who joined in June and July will have to pay the £25 charge, while completely new members are looking at a bill upwards of £70 to cast their vote, based on the price of current standard membership.

Registered support for the Labour Party is a one-off commitment, and becomes meaningless after every election or contest. So, anybody who paid their £3 to vote in last September's leadership election is technically no longer affiliated with the Labour Party.

If you paid to vote as a registered supporter last year, then you must "re-register" that support next week, between 18 July and 20 July, and pay the £25 fee upfront.

Those who cannot afford the £25 fee to register their support are being encouraged by some activists to join one of Labour’s affiliated unions or groups for a reduced fee. For example, people can join the Unite union as a community member for 50p a week.

The deadline for subscribing to these groups is 8 August, when the Labour Party will take register of all people able to vote. However, this date could be subject to change and could vary from group to group.

Affiliated groups and unions include: Unite, UNISON, the Labour Movement for Europe, LGBT Labour and the Socialist Health Association.

A full list of affiliated support groups can be found here: http://support.labour.org.uk