N.Y. Comp. Codes R. & Regs. tit. 16 § 228.4
If, upon conducting a referee test, a gas meter is found to be registering more than two percent fast (98.0% proof), the customer's bills shall be adjusted for that amount that deviates from 100 percent proof for one half of the quantity registered since the last test of the meter for a period not to exceed six years. Where the same meter has served more than one customer since last test, the original test date shall still apply; however, the current customer's bills shall not be adjusted beyond his/her turn-on date. However, if a customer can provide copies of his/her bills beyond the six-year period, the bills will be used up to the time of last meter test. If it can be established that the error is due to an accident or other cause, the approximate date of which can be determined, the bill shall be adjusted back to such date, or a maximum of six years. If, however, the consumer has suffered no damage from said error by virtue of the fact that the meter has registered a quantity of gas less than that allowed for the minimum rate of the applicable rate schedule, no adjustment will be made. No refund will be made if the meter error was caused by the customer's action.
N.Y. Comp. Codes R. & Regs. Tit. 16 § 228.4