CPO interest for delayed payment for land

parents got a letter from revenue seeking income tax payment on interest earned on a late CPO payment for land acquired.

They have a letter/statemen from the county council that made the payment stating they had deducted income tax from from the payment.

Are my parents also liable for income tax on this payment?

Income from late payment is subject to income tax and should have been returned on a form 11 or 12.
If they are low rate tax payers then the tax deducted will cover the tax liability. Get an accountant to do up the return for the relevant year(s) and things should sort themselves out.

Thanks for the the reply