Re: Using my matured SSIA ( up to €7.5k?) to buy back years in my pension.
I'm currently buying back just under five years' notional service by regular contribution under the D/Finance scheme - while I looked into AVCs, I was concerned about the transferrability and they were a little more expensive. The lump sum looked rather attractive (since it would then apply irrespective of future promotions, etc), but doesn't suit at the moment. The main attraction of the Finance scheme versus AVCs is that although the Finance scheme is supposed to be self financing, it does guarantee a link to final salary, whereas with AVCs you've got more risk. And the €8900 should be tax deductible, I think, which will make it look a lot more appealing.
My conclusion was that lump-sum buy-back works out best through the finance scheme, particularly if you feel you have good future promotional prospects - but I didn't spend a huge amount of time on the lump sum option.
I'd suggest asking your AVC providers to run some calculations and see what a year's buy-back equivalent would be, and to find out what their assumptions are in terms of promotion and final salary in doing their sums.