Whichever is later

[Linn]

In the following context, which is later?
"and make payments retroactive to the original filing date (09/15/99) or to Sept. 25, 1985, whichever is later".

[Barb_D]

Is that exactly how it was written? Obviously, anything in 1999 is later than anything in 1985. It's a very strange thing to write, since it's clear what the later date is.