Acting up in Civil Service and returning to lower paid substantive post before retirement

There appears a difference between Fixed and variable allowance and how they are pensioned, fixed being more favourable.

I think it may be the other way around. The variable allowance is more favourable for pension purposes:

"The value of the fixed allowance to be included in an individual’s final pensionable remuneration will be based on the average annual amount of that allowance paid to the employee during the 3 years of reckonable service immediately preceding their last day of service....

...The value of variable allowances to be included in an individual’s final pensionable remuneration will be based on an average of the variable pensionable allowances received in the best 3 consecutive years in the 10 years preceding retirement, uprated to the date of retirement. The most favourable 3-year period, resulting in the highest allowance amount, will be included in final pensionable remuneration."

Civil servants can be in receipt of higher duty allowances for decades, ASC deducted, but pension contributions, not deducted and higher duty is un-pensioned. Union bizarrely allow this money saving tactic, by the civil service. It’s a racket.

Are you sure about that? It would be very unusual for civil servants to be disadvantaged versus the wider public service. I think this Circular applies to both? https://www.gov.ie/pdf/?file=https:...457408d9ac24104adb2d561f42adcec.pdf#page=null

Could you provide information re the retention of the acting allowance if in receipt for 5 years that would be very helpful

Only in relation to teaching. I am not sure if it extends beyond that. See 2.1 here https://circulars.gov.ie/pdf/circular/education/2000/42.pdf
 

It is interesting. But it relates to a person employed in a more senior role under a fixed term contract. This is not generally the case in an acting up situation. Fixed term contract employees have specific rights ( https://www.citizensinformation.ie/...ployment/rights-of-fixed-term-workers/#b96346).