After you file

No, it's not a scam- look it up online and you'll see the FTB has posts about FTB 3904 on their website.  However, I'm also confused about the paycheck stubs part.  Do they want stubs from last year and if so, how many?  Or do they want stubs from this year?  I've been hunting online, but so far haven't seen a response.  Has anyone spoken to the FTB about this and gotten an answer?  I also received one of these letters and am hung up on this particular detail.