The former MLA whose private member's bill paved the way for Stormont's first official opposition believes it needs more resources to challenge the executive.
John McCallister said the £60,000 which will be allocated to the UUP and SDLP is dwarfed by the "huge machine of government".
The former NI21 deputy leader, who lost his assembly seat earlier this month, introduced the legislation that will enable the creation of an opposition on Wednesday.
His bill received royal assent in March this year.
Where previously anybody who opposed Stormont's governing coalition was relegated to a corner of the assembly chamber, Mr McCallister's bill creates defined entitlements for those who designate themselves 'opposition'.
The entitlements are open to any 'qualifying party' whose representatives make up more than 8 per cent of Stormont's 108 MLAs – this includes the UUP and SDLP but excludes Alliance, the Greens, People Before Profit and the TUV.
In addition to a financial package, which the Assembly Commission has set at £60,000-a-year, the opposition leader will be given the opportunity to question ministers in the assembly chamber.
Speaking rights will be enhanced too, ensuring the opposition parties get to address the assembly more than their numerical party size would automatically entitle them to, including a minimum of 10 days per year set aside for 'opposition business'.
The opposition also has an automatic right to chair Stormont's Public Accounts Committee and to get a seat on the assembly's business committee.
However, Mr McCallister said the resources need to be increased.
He said what was being offered to the parties at present was less than the salary of many of the special advisers afforded to ministers.
The former South Down MLA said boosting the amount of cash available could come from money saved by reducing the number of assembly committees.
He also believes Stormont's expenses watchdog should be tasked with deciding how much is allocated to the opposition, rather than leaving it to the Assembly Commission.
"I think the Independent Financial Review Panel should be the ones who look at what's acceptable in terms of finances and what the opposition parties realistically need," he said.
"When you look at what the opposition parties are up against – up to a dozen ministers with special advisers plus all the civil service staff – it dwarfs what is available to the UUP and SDLP."
Mr McCallister said additional cash would fund the development of alternative policies.
"Government has all the advantages, whereas opposition is always disadvantaged, so if you're going to seriously challenge the government you need the necessary financial support," he said.
"Creating a well-resourced opposition is essential for a healthy democracy and I think our political system is now mature enough to cope with that."
When The Irish News asked Ulster Unionist leader Mike Nesbitt if he believed the assembly needed to increase funding, he responded: "Our current focus is on the quality of our opposition team, not the quantity of resources. We are very confident that our 16 MLAs are up for this as are the SDLP`s."
