DUDE, what’s my age?

That’s the question Ashton Kutcher should be asking. Demi Moore‘s toyboy claims to have turned 26 on February 7 — but the Planet Tab Investigative Team has discovered a document that could be the smoking gun in proving the “Dude, Where’s My Car?” star is actually 30!

According to a bazillion press clippings, actor Christopher Ashton Kutcher was born Feb. 7, 1978, in Cedar Rapids, Iowa. But Los Angeles County Registrar’s voter registration records show a Christopher Ashton Kutcher who was born in Iowa and currently residing in Beverly Hills with a birth date of Feb. 7, 1974.

Pure coincidence? A clerical error? Call us skeptical, but we think not!

If Kutcher really IS 30, that would make his so-called May-September romance with 41-year-old Demi more like a July-September romance and take some of the sizzle out of the relationship.

Ashton’s representatives insist that he was born in 1978 and when he appeared on “The Tonight Show” back in January 2003, Kutcher himself confirmed the same thing to host Jay Leno.

But if that’s the case, why do the L.A. voter rolls have him listed as 30? Hmmm, could it be “The Butterfly Effect” . . . or are we just being “Punk’d”?