A Westminster committee is to open an inquiry to look at the implications of the Irish border backstop in the Brexit deal.
The Northern Ireland Affairs Committee is seeking written evidence on four issues in the EU withdrawal agreement.
The backstop is an insurance policy to avoid a return to a hard Irish border if no other solution can be found through a wider trade deal.
MPs opposed to it have vowed to vote against the plan next month.
The backstop, if it took effect, would see Northern Ireland only continue to follow some EU rules and would require extra checks on goods coming into Northern Ireland from Great Britain.
The committee's inquiry will look at how implementation of the backstop would work in practice for Northern Ireland.
'Backstop is central concern'
It is also seeking evidence on Northern Ireland's preparedness for a no-deal Brexit; scrutiny of the mechanisms in the Brexit deal governing the backstop and the steps that need to be taken during the transition period - which runs until December 2020 - to secure an overall EU-UK trade deal that removes the need for the backstop.
The inquiry will explore the impact extra checks on goods travelling between Great Britain and Northern Ireland under the terms of the backstop would have.
The committee's chair Andrew Murrison said the backstop had emerged as a "central concern" in the government's agreement.
"Uncertainties remain about the effectiveness of no-deal planning," he said.
"My committee's inquiry will explore the implications of the agreement for Northern Ireland."
The deadline for written submissions to the inquiry is 17:00 GMT on 21 January 2019.
MPs are due to vote on the government's withdrawal deal in Parliament in the week beginning 14 January.
In a separate development, Northern Ireland civil servants are to meet government ministers to discuss Northern Ireland's preparations for a no-deal Brexit.
The announcement was made by Cabinet Office Minister David Lidington told the Commons.
He was asked by Democratic Unionist Party (DUP) MP Paul Girvan about what money would be given to the Northern Ireland Civil Service to plan for a no-deal Brexit.
Mr Lidington said "consequential sums" of money would flow to the Northern Ireland Civil Service as a result of the cabinet's decision and that civil servants would have time on Wednesday to make their case directly.