PAEA 2007 required funding of accrued liabilities for the USPS, same as PPA 2006. However, other governments in the US are not required to fund any liabilities for post employment benefits, at all, as they are excluded from both ERISA 1974 and PPA 2006.

https://www.congress.gov/109/plaws/publ435/PLAW-109publ435.p...

Page 55 discusses setting money aside for retiree healthcare benefits:

>Not later than June 30, 2007, and by June 30 of each succeeding year, the Office shall compute the net present value of the future payments required under section 8906(g)(2)(A) and attributable to the service of Postal Service employees during the most recently ended fiscal year.

"Net Present Value" is accrued, i.e. benefits owed to current and past employees.

It makes sense to require an organization to set aside money it promised to pay someone...otherwise organizations would just go around paying people today with future taxpayers' money (which is what governments literally do).

Page 53 discusses the same for defined benefit pensions. All of the present values are of accrued benefits, not projected benefits.

However, I do suspect this was a clever way to handicap the USPS specifically, since it did not apply to any other governments such as state/county/city.