Rebecca, I wouldn't count on your HR system to ensure that part time staff are working their contractual hours (and hence getting their contractual holiday entitlements). That looks to me to be more of a management responsibility to ensure that the planned working pattern properly reflects the contract.......
Out of curiosity, how are you paying people who work more than their contracted hours today? By overtime? If so, and you intend to calculate holiday entitlements based on part-time contract hours + overtime, if you want equal benefits for ful and part-time staff, should you not increase holiday entitlement for full-time staff who do overtime?

In reply to Ray:

Hi Ray, thanks for the reply. It's not about tracking contractual/working hours (that is done elsewhere) but more of a technical question about how the HR system can be configured to automatically calculate a fair bank holiday allowance based on both hours and normal working pattern, i.e. the working pattern where they either do or don't work any Mondays which is when many UK bank hols fall.  Has anyone been able to set this up in their HR systems in a way that works - we are using Successfactors

In reply to Rebecca:

Thanks the clarification Rebecca. To be honest, in the companies I have worked in, this has generally been done in the time and attendance / workforce shift-planning tool as opposed to the HR system - probably because shifts have been 24/7 all the year round - in some cases with 70+ variations of shift models for several thousand people in 2 countries and different time-zones/bank holidays - calling for a high degree of sophistication.
Have you discussed the need with your SuccessFactors support team? They must have encountered this situation in other companies and be aware of the the solutions that have been found;

In reply to Ray:

We give all our part-time and condensed hours staff holiday entitlement in hours rather than days totalling both our holiday and "closure days" entitlement and also request that they "book" the closure days at Christmas and Easter into the system (these will be automatically "approved" by the manager) as well as their holiday requests.

Are you getting any advice from the provider at all? I used to work for an organisation that had a really outdated system (ADP). I have to calculate everyone's pro-rata b/h allowance, manually add it to their balance and then book any b/hols they were due to work. If I was to source a new system I would definitely be asking the provider how this could be automated and looking at other providers if it is not something they can help with.

In reply to Elizabeth:

Thanks Elizabeth. We actually have in house expertise in the system but this requirement seems to be testing what's on offer! I'll say no more...