They have now been told it will cost them more if they opt to ditch the trackers and lock in to fixed rates.
Around 33,000 tracker mortgage accounts were transferred to AIB from Ulster Bank in July.
But it has now emerged that another 10,000 tracker mortgages are still with Ulster Bank and have yet to transfer to AIB.
AIB said: “Approximately 10,000 customer accounts have yet to transfer and it was always envisaged that those customer accounts would transfer at a later date.”
Yesterday, Ulster Bank announced a rate increase of 0.75 percentage points on its remaining fixed-rate products.
The new rates will apply to two- and four-year fixed-rate mortgages, as well as the four-year fixed-rate green mortgage. The seven-year fixed rate will be removed from sale. These changes take effect immediately.
Tracker mortgages have become very expensive after 10 European Central Bank (ECB) rate rises.
Variable rates are not impacted by this increase.
The transfer of the Ulster Bank mortgages to AIB, following the agreement of the €5.7bn sale, has been beset with problems.
Earlier this month, AIB was forced to offer thousands of tracker mortgage customers who have transferred to it from Ulster Bank a four-month reprieve on the most recent ECB rise in interest rates.
The bank said about 33,000 tracker mortgage accounts that were transferred to AIB from Ulster Bank in July would benefit from the freeze on rate rises.
AIB has also struggled to take payments for mortgages from the former Ulster Bank customers.
The rate-rise freeze comes after the bank was forced into a U-turn last month. It had written to a number of former Ulster Bank tracker customers mistakenly telling them their monthly repayments would have to rise by up to €600 a month.
It withdrew the letter and said it was a mistake, as exclusively revealed by the Irish Independent.
AIB cancelled direct debits for Ulster Bank tracker mortgages
It later emerged that a small number of former Ulster Bank tracker customers had their direct debits cancelled. These direct debits had been set up to pay mortgages.
AIB said the four-month deferral was “in recognition of the confusion and concern that may have been caused for these customers by a letter they received last month”.
The announcement means higher payments that had been due to kick in from next month, on the back of the ECB’s most recent rate rise in July, will not do so until February of next year. The decision will cost AIB several million euro.
The four-month moratorium means homeowners with the affected tracker mortgages will save money on their monthly payments. How much these savings come to will depend on the amount owed and time remaining on the mortgage.
For someone with about 10 years remaining and an outstanding mortgage balance in the region of €120,000, the savings will amount to about €14 a month, or €56 in total.
AIB has confirmed that there will be no cost or clawback of payments to customers for these deferrals.