2 U.S.C. § 4522: Deductions for withdrawal

When any Member or Delegate withdraws from his seat and does not return before the adjournment of Congress, he shall, in addition to the sum deducted for each day, forfeit a sum equal to the amount which would have been allowed by law for his mileage in returning home; and such sum shall be deducted from his compensation, unless the withdrawal is with the leave of the Senate or House of Representatives respectively.