If he retains his Te Tai Tokerau seat on September 20, the new alliance will be able to claim its percentage of the party vote even if it falls under 5 per cent.
If the Internet Party were not tied to an electorate seat, it would have to get 5 per cent of the party vote on its own before getting seats in Parliament.
For its part, the Mana Party will almost certainly get a lot more profile than it otherwise would during the campaign.
The Internet Party is likely to stump up with a bigger war chest than Mana could though the extent of joint campaigning has yet to be announced.
The Electoral Commission donation declarations yesterday revealed that Mr Dotcom, an internet mogul, gave the Internet Party $250,000 on May 14.
Mr Harawira will be joined at Parliament today by Internet Party chief Vikram Kumar for the announcement. It is not known if Mr Dotcom will be there too.
He is not a New Zealand citizen and is therefore not eligible to be a candidate.
He also faces extradition to the United States where he is wanted on copyright, racketeering, money laundering and wire fraud charges.
The parties' talks were revealed by the Herald on Sunday in March.
Mr Harawira last night said his party had "come to a clear majority decision".
Party member and former Green MP Sue Bradford has spoken against the proposal from the outset but it is thought to have the support of not only Mr Harawira but also president Annette Sykes and vice-president John Minto.
The deal will present the Labour Party with a dilemma in Te Tai Tokerau where Kelvin Davis has been selected to stand against Mr Harawira.
The party will have to decide whether to encourage Labour supporters to strategically support Mr Harawira over Mr Davis.
