Incremental skips in Public Service

There's no real hard and fast rule, as far as I know. The short answer is "it depends".

I've posted about this before, but I was secretary of the IMPACT (now Fórsa) branch around the time that the recruitment moratorium finished at my old job and was involved in loads of cases around what you're describing, albeit for slightly different reasons. We were a public sector organisation, but not full civil servants. This meant we were not part of the common recruitment pool, ineligible for interdepartmental positions and subject to the rules and regulations of the open comps.

The roles and grades were identical to the civil service 'proper' but instead of CO, EO, HEO, AP etc., the grades were named slightly differently, but with identical Ts &Cs. So we had AA, EO, SEO, SAO etc. For certain HR units, usually the smaller ones, this meant that they shoved people back to point 1 on their new scale, even if it meant they lost money. Two quick examples:

An AA working there 15 years (on about €40k) got promoted to EO via open comp. New HR guys said "that's not the same as CO, so you're back to point 1 on the EO scale" (approx €30k). He appealed, they said no. He asked us to make representations on his behalf and they wouldn't budge. Kept saying they were perfectly within their right, even after they were shown evidence of this occurring elsewhere, including @ DPER's own offices. In the end, we convinced them to put him at point 3 or 4 on the EO scale, and he'd get no increments for either 3 or 4 years, until he'd 'caught up'.

A different AA was in the same boat, successful at open EO comp and had been told he was starting at point 1.....about a 20% pay cut for him. There was a couple of week's worth of back and forth trying to sort it out, but they wouldn't budge. He was thinking of refusing the offer, but wasn't sure how that would affect him going forward. He had also applied for an open CO competition that was running at the same time, but hadn't concluded yet. He was successful in the CO comp and got placed in the SAME DEPARTMENT as his EO offer. He took the CO post, moved over to the new department as a CO at his current point on the scale, then accepted the EO offer, meaning he began at point 6 or 7 on the EO scale.

Absolutely barmy stuff, caused completely by the actions of one pig-headed idiot in HR in the new place. Both times they were small, independent, autonomous bodies as opposed to proper Depts. Literally a mini-Hitler running the show and refusing to entertain any notion they were in the wrong.

They updated the legislation just before Covid hit to cover these types of situations (.pdf linked here) but left in the bit about local HR having the final call on what is equivalent to an established grade, and what isn't. And that's a load of BS.