Thank you. Our company recently changed employment policy regarding vacation pay. Previously vacation time was earned monthly and able to accrue for 24 months. There was not a hard stop date, but eligibility was determined as of Jan. 1. Now the new policy

Previous personnel policy stated "Vacation allowance is based upon years of service with xxx. Annual vacation eligbility is deterrmined as of Jan. 1.
Full time exeomp staff 20 vacation days or 1 2/3/ earned monthly.
Vacation leave begins to accrue from an employee's date of hire. Any accrued vacation leave may not be used before the completion of six months probationary period. After probationary period earned vacation is available to be taken as earned but must be schedule with the supervisor's advance approval and consistent with the work needs of xx. Vacation leave may be accrued up to 24 months before it is forfeited"

New policy
Annual PTO earned according to number of years of service. All time accrued in a calendar year must be used by Dec. 31 of the following year. If PTO is accrued the prior calendar year and is not used by the end of the following calendar year, it will be lost. Effective 9/8/16

On our ADP portal, it showed our accumulated eaned time.

My question is this:
Prior to September 8th, any previously earned vacation time accrued, will be recalculated based upon the new policy with a Dec 31 date instead of the 24 month accrual. In many cases, long-time employees will end up losing previously earned time.
Can they retroactive recalculate our accrued earned vacation time? I understand completely about any time earned going forward, but concerned about the previously earned time.
Can someone answer this question?