A Parliamentary committee is to examine the Northern Ireland protocol.
Under the arrangement, the province will continue to enforce EU customs and follow the bloc's rules on product standards.
The finer details of how it will work are still being negotiated.
The announcement of the inquiry by the Northern Ireland Affairs Committee follows the publication of the Government's Internal Market Bill this week.
The legislation, designed to ensure goods can move freely and without charge within the UK, contains powers relating to internal trade that conflict with the withdrawal agreement and Northern Ireland protocol.
Secretary of State Brandon Lewis will give evidence to the first session of the committee next Wednesday.
The inquiry will anticipate and react to developments in the UK-EU trade negotiations, UK politics and in the implementation of the protocol.
Its terms of reference include examining the preparedness of government, public services and businesses for the arrangement coming into force on January 1.
It will also look at the implications of the protocol for the economy of and investment in Northern Ireland, as well as the consequences for devolution.
Committee chairman Simon Hoare said: "The Northern Ireland protocol will be a significant change for all walks of life in Northern Ireland.
"It could change operation of cross-border services, trade within the UK, trade with the Republic of Ireland and citizen's rights.
"The Internal Market Bill published on Wednesday interacts with the protocol and we need to examine what outcomes will come of it.
"Negotiations between the UK and EU on the precise form of some aspects within the protocol are ongoing. We will be asking the Secretary of State about these matters at our first hearing.
"I know that the committee will be keen to establish how the protocol now apparently undermines the Good Friday Agreement when two months ago it did no such thing.
"With events moving so rapidly and crunch time on negotiations fast approaching, it's an absolute necessity that we have a rolling and flexible inquiry into the implications of the protocol, deal or no deal."