These are pretty new to me so I had a couple of basic issues I am not clear on yet:

Does the employer have to allow a carry over year to year or can the employer apply a "use it or lose it" policy?

Can the employer set different amounts of reimbursement for singles vs. employees with dependents?

The employer does not have to allow rollover of the amounts, but then, what would be the purpose of offering the HRA? If it does not roll over, there may be no incentive for participants to lower their health expenses, thus defeating the purpose. (I imagine it depends on the other parameters of your plan.)

Second question, yes, there should be no problem with the employer setting these limits; the IRS has given great lattitude to employers. Just be careful that a large marjorityl of your highly compensated employees don't fall into a category that receives a higher reimbursement levels or you could have problems.