Brendan, I've rewritten this post a few times as i'm confused with the Revenue information! - from Revenue website in relation to MIR below from April 2013
'Switching lender or mortgage type to achieve a better interest rate is not the same as taking out a new loan. However, a new mortgage where you move home and take out a mortgage with a new or existing lender is eligible for relief.
A mortgage taken out from 1st January 2004 to 31st December 2012, used to purchase, repair, develop or improve your sole or main residence, situated in the State eligible for mortgage interest relief until 31st December 2017 (see rates/ceilings chart). Mortgages taken out after 31st December 2012 will not qualify for mortgage interest relief.
Mortgages taken out after 31st December 2012 will not qualify for mortgage interest relief'
I think it's somewhat confusing. First of all switching lender and switching mortgage type are vastly different. I've never switched mortgage but as far as I'm aware, a switch involves the full redemption of the original mortgage and a new mortgage then being taken out with the new lender and as it is a new mortgage taken out after 31/12/2012 is not eligible for MIR. The Revenue information is telling me that a remortgage with a new lender or move to a different rate prior to 31/12/12 it will not reset the MIR clock to 2017 either - this I assume was to prevent a flood of token mortgage changes prior to 31/12/12 attempting to avail of the extended relief to the 2017 deadline. If you did move however or drew down a new mortgage before 31/12/2012 you could have availed of MIR to 2017. Any change from 2013, MIR is a relic of the tiger and not an option? Like all things Revenue, its complicated and I'm open to correction!