Seems a bit high.
People find it hard to understand these figures. But you are comparing 2010 euros with 2030 euros (or whenever you will be making the additional repayments)
If you have 20 years left on the mortgage, you are, in effect, borrowing €7,200 for 20 years. €7,200 @ 4% compound interest over 20 years amounts to €15,800
Look at it another way if you put €7,200 of
this money on deposit at 4%, it will be worth €15,800 after 20 years. Check out this Key Post
Should I use a lump sum to reduce my mortgage?
If you have 30 years left, it would amount to €23,400.
Did you reduce the repayment as well? If you did, then that alone would extend the term of your loan.
What interest rate are you on?
Did you have arrears at the time which they capitalized?
When did this happen and when was the mortgage due to finish?
What amount was outstanding when you got the moratorium? Did that include arrears?
Brendan
Update: I see that your accountant has already advised you on
this issue.