Age Action, meanwhile, says buying power of the state pension has dropped.
The fuel allowance is set to increase by at least 3 euro 50 in tomorrow's Budget.
The number of people eligibility for the payment is also set to be widened under plans being considered by government.
Also set to feature in the 4.7 billion euro spending plan is funding for an extra 1,000 special needs assistants and an increase to the SUSI grant for students.
Political Correspondent with the Irish Examiner, Daniel McConnell, says spending's being focused on areas that missed out in recent years:
The buying power of the state pension has dropped by over ten euro a week since 2019.
That's according to the charity Age Action, which is calling for a 15 euro increase in tomorrow's budget.
It says two more years of the same increase would bring it up to a third of the median income.
Age Action policy officer Nat O'Connor says the state pension should be automatically adjusted for inflation