A snap Stormont Assembly election in December would cost the public more than £6.5million, the chief electoral officer has said.
Virginia McVea said plans are being made for a potential poll on December 15.
Secretary of State Chris Heaton-Harris has insisted he will call an election if Stormont's power-sharing Executive is not restored by midnight on October 28.
Read more: Snap Stormont election in December would be 'diabolical', UUP says
He told MPs on Tuesday he "can't see the space" for any emergency legislation at Westminster to potentially avert the legal requirement for an election if no Executive is formed by the deadline.
The Alliance Party has submitted an Assembly recall petition in a fresh bid to re-establish the devolved institutions.
Stormont has been in limbo since February with the DUP blocking the restoration of the Executive and Assembly in protest over Brexit's Northern Ireland Protocol.
Ms McVea said final spending from the last Assembly election in May is still being collated, but she gave an approximate figure for how much another poll would cost.
She told BBC's Good Morning Ulster: "In broad terms it will be over £4.5m for the general administration, and then candidates get support with their mailing, I think that's over £2m, so it will be over £6.5m."
Ms McVea said preparations have been continuing over recent weeks due to the challenges of holding a potential winter election.
She said: "On the basis of the legislation as it sat over the last month or so in particular we have been looking to see what we could put in place if it were to happen.
"Because obviously just before Christmas is a very difficult time for primary schools and church halls and also for people - we need 5,500 people to come and work for us to make this all happen - and in that week before Christmas or so that's a very busy week."
More than 600 venues have been contacted which could be used as polling stations to hold around 1,400 ballot boxes, Ms McVea said.
She added: "I have to express my gratitude for the vast majority have come back to us, confirmed that they will support their local communities and work with us even though it's a difficult time.
"And the same with staff. I think there were over 8,000 letters went out to people who may work for us and the vast majority are coming back to say they will try and hold that date."
Ms McVea advised voters to contact the Electoral Office if they need their digital registration number.
She said: "Please contact us to get your digital registration number in case you might need to ask for an absent vote, particularly people with elderly relatives or those who may be frail. We can anticipate if it happens this will be dark and wet most likely."
The Alliance Party has 17 MLAs and so will need the support of other parties to achieve the 30 MLA signatures required to recall the Assembly.
Its leader Naomi Long said: "We are in an unprecedented period of uncertainty between Parliament and the Assembly.
"As things stand, next week the caretaker ministers are removed from office and departments are left without direction at a time when Westminster is in chaos.
"In that context, and considering the cost of living and cost of business crisis, it is reckless and irresponsible in the extreme to allow the institutions to drift into deeper crisis, dragging in its wake our public finances and public services."
READ NEXT:
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- Call a snap election if Stormont is not restored by October, shadow Northern Ireland secretary says
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