In a recent bridge game, the contract was 2C doubled. The contracting team discovered, at a point in the game after a trick had been played that the opposing team had reneged. They assert that there should be a two trick penalty, and that those two tricks should be scored below the line. Since the contract was made, with two overtricks, the result would be that the contracting team earned a game since the renege gave them two extra tricks below the line, and that was doubled. Opposing team argues that they did not double the contract into game, and the four should be treated as overticks. I had never heard that a renege was a below the line penalty...this is new to me. I cannot find any information regarding this. Can you help?
Everything below still stands, but it now occurs to me that it may not address the correct aspect of the question.
The renege having been noted, and the appropriate penalty adjustment made as described below, the play of the hand is completed.
At this point the deal is scored according to the contract as originally bid, with the trick results as played and adjusted for the renege. If the contract is made, points below (and possibly also above in the case of overtricks) the line are scored by Declaring side; otherwise points above the line are scored by Defending side.
In this sense, if the determination of made or set was decided by the penalty adjustment for the renege, then said tricks can be said to be properly scored below the line. This may be the confusion that OP is originally inquiring about.
The Laws or Rubber Bridge (2014) clearly state:
Law 64 – Procedure After Establishment of a Revoke
When a revoke has become established,
A. if the offending player won the trick on which the revoke occurred, (penalty) that trick and one of any subsequent tricks won by the offending side are transferred to the non-offending side (if no subsequent trick was won by the offending side, only the revoke trick is transferred).
(For the scoring of transferred tricks see Law 77.)
Law 77 – Transferred Tricks
A trick transferred through a revoke penalty is reckoned for all scoring purposes as though it had been won in play by the side to which it had been awarded.
Declarer plays in 3♥ and takes eight tricks. A revoke by a defender is found to have been established, with the penalty determined to be two tricks. Two tricks are transferred from the offenders to declarer, who therefore has 10 tricks. Since he bid only 3♥, he scores 90 trick points, which count toward game, and 30 premium points for the overtrick.
Note that Law 77 and accompanying example clearly states that the transferred tricks are transferred only in regards the play; not in regards the contract. This is consistent with the scoring described in Law 72 (my emphasis):
Law 72 – Points Earned
The result of each deal played is recorded in points, which fall into two classes:
A. Trick Points. Only declarer’s side can earn trick points and only by fulfilling the contract. Only the value of tricks named in the contract may be scored as trick points (see Law 81). Trick points mark the progression of the rubber toward its completion.
B. Premium Points. Either side or both sides may earn premium points. Declarer’s side earns premium points by winning one or more overtricks, ....