The British government has left Northern Ireland businesses suffering "frustration, anxiety and fear" due to Brexit uncertainty, Labour has said.
Shadow secretary of state Louise Haigh said "thousands of businesses still do not know the bare basics" of the trading regime at the end of the year.
Northern Ireland minister Robin Walker insisted the British government is helping traders "prepare for the end of the transition period".
Asking an urgent question, Ms Haigh told the Commons: "Northern Ireland needed every second of this transition year to get ready for the biggest changes to their trading relationship it has ever known, but vital time has been squandered.
"First denying any checks would take place at all and then the extraordinary spectacle of the government threatening to tear up its own oven-ready deal and breach international treaties they had signed into law...
"The result of this recklessness, this incompetence, is that thousands of businesses still do not know the bare basics of how they will trade with Great Britain in just six weeks' time."
Mr Walker said: "We continue our work to implement the Protocol in a pragmatic and proportionate way that minimises the disruption to people's day-to-day lives and preserves the gains of the 22 years since the Belfast Good Friday Agreement was signed.
"We're helping traders to prepare for the end of the transition period. We've published business guidance in August and are updating it all the time as arrangements are finalised. We've established the trader support scheme backed by £200 million of Government funding, with more than 7,000 businesses now signed up and hundreds more joining them every day."
Conservative Simon Hoare, chairman of the Northern Ireland Affairs Committee, said: "It is 43 days, minister, until December 31 and Covid-hit businesses in Northern Ireland are exasperated, and I share that exasperation."
MPs also pressed the British government to develop an implementation period to help Northern Ireland businesses deal with changes caused by Brexit.
The SNP's Alyn Smith (Stirling) raised concerns over the risk of "organised crime focusing on Northern Ireland" because of the lack of preparation, adding: "This just isn't ready yet. Northern Ireland needs an adjustment period - are there preparations for that?"
The DUP's Westminster leader Sir Jeffrey Donaldson added: "There's cross-party and cross-community support for a period of time for implementation of these measures to allow our businesses, supermarkets and others to prepare properly."
DUP MP Sammy Wilson (East Antrim) asked if the British government would "act unilaterally" to protect the Northern Ireland economy under provisions set out in article 16 of the Withdrawal Agreement.
Mr Walker replied: "As we have shown through the United Kingdom Internal Market Bill where we need to take steps to protect our commitment to unfettered access and the UK internal market we will."
SDLP leader Colum Eastwood said lives and livelihoods are at risk because of the "ineptitude" of the Government.
He added: "If there is no deal on data-sharing with the EU by the end of this transition period, there's a real risk that health services in Ireland won't be able to carry out cross-border contact tracing.
"Brexit is a total mess of this government's making. The pandemic, Covid, is a mess and a crisis made worse by this government's handling of it. Lives and livelihoods are at real risk because of the ineptitude of this government.
"When will people in Northern Ireland have some confidence that contact tracing will be able to continue across the border?"
Tobias Ellwood, Conservative chairman of the Commons Defence Select Committee, said the UK must "bury the myth that we might consider deliberately breaching international law".
Mr Ellwood added: "When it comes to re-establishing greater Western resolve, 2021 could be a big year for the United Kingdom as we host Cop26 and we take on the presidency of the G7.
"But this can only happen if we secure a trade deal with the EU, if we protect our overseas aid budget, if we complete a costed Integrated Review and if we bury the myth that we might consider deliberately breaching international law."
