Latest figures from the Department of Finance show 74% of mortgages in long-term arrears have not yet been restructured.
The figure represents a drop of 1% over a one month period from last November to last December.
The Department said there had been a "significant rise" in the number of split mortgages, from 2,521 last August to 6,239 by the end of December.
The figures are based on data from AIB, Bank of Ireland, Permanent TSB, ACC, KBC Ireland and Ulster Bank.
Almost 14,000 permanent mortgage restructures had been agreed by the end of last year, according to the figures, representing 18% of all mortgages that were in arrears for 90 days or more.
However no restructuring deals had been agreed for 59,226 mortgages in long-term arrears, representing 8.5% of all mortgage accounts.
The number of temporary solutions agreed in December stood at 6,571 – down slightly from November.
Overall, the number of mortgages in arrears for 90 days or more was down slightly in December, falling from 81,156 to 79,782 accounts.
The number of mortgages in arrears for one day or more fell slightly to 114,921.