Many small retailers and other businesses are getting a three-month rates holiday, amid the ongoing coronavirus crisis. But elsewhere in the UK, a 12-month freeze has been introduced.
Rates can account for around 20-30% of many business monthly outgoings, and it has been warned the failure to bring Northern Ireland in line with Great Britain could be "exponential" and see "hundreds if not thousands" of companies "not coming out of the crisis".
Glyn Roberts, chief executive of Retail NI, said: "Given rates is the only tax power Stormont has, it is vital they use the rating system to get as much relief out to support businesses.
"Why are we only getting three months, while everyone else is getting 12 months?
"They are dealing with the same problems (as businesses elsewhere).
"We should be doing as much as possible to support businesses through this to ensure they can return. In the short-term we need to be using everything to support (firms)."
In his budget this week, Finance Minister Conor Murphy announced the Small Business Rates Relief scheme providing almost £20m of relief to 27,000 small businesses, while rates would also see a 12.5% cut.
Asked whether the Executive would be re-examining the 12-month business rates freeze, a spokesman for the Department of Finance said: "So far the Executive has provided significant support to businesses with over half of all available Covid-19 funding (£470m) being used for business support measures.
"This includes the £100m rates support package which will provide a three-month rates holiday to help all businesses here, unlike GB where the rates holiday is only for certain businesses.
"In addition to the rates holiday, as announced yesterday in the Budget the non-domestic regional rate will also be reduced by 18% - benefiting all businesses. This is being funded from the Executive's existing resources on top of the Covid-19 funding.
"Rates bills will also be delayed until the last possible moment, with the first bills to be issued in June. These measures will be kept under review and we will take further steps should we deem it necessary."
But Mr Roberts said: "The price will be hundreds if not thousands of businesses not coming out of this crisis, and being able to reopen.
"The cost is exponential. We are dealing with the same crisis."
He said businesses from across the sectors would be impacted, including those such as small retailers, hospitality and the wider manufacturing industry.
"We pay the highest business rates in the UK. Before this, it was a huge burden, and now it's even more of a colossal burden."