Following on from Jeff Moden and his suggestion of sophistication, you should also consider whether the benefit is non-contributory, contributory or a loan.

If non-contributory is there a limit, is it a simple cash sum or a pay percentage, is there a penalty clause (first $50 on dental treatment).

If contributory, is there a limit on employer contribution, does it match employee contribution up to that limit, is there a scale for employer contribution e.g. pensions being 1% to 15% of net or gross.

Does the benefit affect National insurance contributions, if payable, how is this calculated.

If the benefit is a loan that will need paying back, does that feed into the pay deductions table and should it be taxable or non-taxable.

Yes it seems like homework but you have to think about the entities you are modelling.

Good luck