My past employer owes me a lot of back pay. Is there a statute of limitations for how soon I would have to take them to court if I had to do so? If there is, does that start counting down from my first missed paycheck or my last?
I believe the statute of limitations for unpaid wages claims is 6 years, since the Washington Legislature amended RCW 4.16.040(2) in 2007 (see link below) to specifically state that the statute of limitations on accounts receivable is 6 years, and that accounts receivable include "any obligation for payment incurred in the ordinary course of the claimant's business or profession, whether arising from one or more transactions and whether or not earned by performance." This most likely covers your situation.
The time period starts running from the first missed paycheck, because that is the point at which you became aware you were being harmed by your employer's refusal to pay you.