1. The first ground on which it is alleged that the proceedings of the commissioners were erroneous is, that they overruled the motion to dismiss the petition for abate- , ment. The ground of this motion was, that the corporation had not filed a list of their estate and property duly verified within the time specified by the assessors, according to the requirement of St. 1857, c. 306, § 3, which was in force when the tax in question was assessed. But we think the answer to this objection is, that the corporation proved that there was good cause for the omission to file such list. The only defect in the list was, that the agent of the corporation did not make oath that it was a full and accurate list, until after the time designated for bringing it in had expired. But it is shown that this omission was caused by the assessors themselves, who expressly told the agent that they did not wish him to verify the list by his oath, and that the omission of such verification should not in any way prejudice the rights of the corporation. If this is not good cause for a failure to comply with the strict letter of the statute, it is difficult to imagine any case, which would relieve a party from the consequences of such omission. Yet it is clear that the legislature had in view cases where a party might be prevented from a seasonable compliance with the requisitions of law in some particular, and expressly provided that it should not deprive him of his remedy by appeal, if the commissioners should be satisfied that there was good reason for the omission. The case is very different from Winnisimmet Co. v. Chelsea, 6 Cush. 477, cited by the petitioners. In that case there was a failure by the tax payers to bring in any list to the assessors at any time. There was an entire omission to comply with the statute. Such is not the case here. The law was complied with in all essential particulars. A list duly sworn to was filed with the assessors before any application was made to them for an abatement of the tax. The only defect was that it was not sworn to within the time required by law. This was a defect which might be cured without danger of infringing on the rights of any one.
If it were necessary to the decision of this case, we should be *549strongly inclined to hold that this objection to the doings of the commissioners is not open in this proceeding. The commissioners are authorized to determine whether there was good cause for a failure to bring in the list seasonably. St. 1857, c. 306, § 3. By this provision it would seem that the jurisdiction of this question is vested exclusively in them, to be decided in the exercise of a sound judicial discretion. If this be so, then it is clear that their adjudication upon it cannot be reviewed by this court in a proceeding in the nature of a writ of error.
2. It is next objected that the commissioners erred in refusing to inquire whether certain lots owned by the corporation were not undervalued by the assessors and taxed for a sum less than was warranted by their actual value. This objection seems to us to proceed on a misconception of the nature of t-he authority and jurisdiction vested in the county commissioners over the subject matter. They have no power to increase the tax assessed on any item of property belonging to the applicant. Even the assessors could not lawfully exercise such a power after the valuation has been once made and the assessment completed. The only authority which the assessors or the commissioners can then exercise is to abate the tax, if in any respect it is excessive by reason of over valuation. This is the extent of the power vested in them. Rev. Sts. c. 7, §§ 37-41. When therefore, as in the case at bar, a tax is assessed on an individual or corporation by a valuation of the separate parcels of real estate belonging to them, and it is proved to the satisfaction of the assessors or the commissioners on an application for an abatement of the tax that any parcel or lot is overvalued and assessed for a greater sum than its actual market value, the applicant thereby proves that he is taxed at more than his just proportion, and is entitled to a reasonable abatement. But proof of such over valuation does not open the inquiry whether other lots have been assessed at too low a rate. The city or town cannot ask that the valuation and assessment on other property of the applicant shall be raised in order to make a set-off against that part of the assessment which is shown to be *550excessive. They are concluded by the judgment of the assessors.
3. The remaining error insisted on by the petitioners is, that the commissioners awarded to the corporation the costs incurred by them in prosecuting their application for abatement. In this respect the commissioners exceeded their jurisdiction, and their judgment was erroneous. A party who obtains an abatement of his tax is entitled only to be reimbursed out of the treasury of the town to the extent of the abatement allowed, if his tax has been paid, "together with all charges.” Eev. Sts. c. 7, § 42. Gen. Sts. c. 11, § 48. This provision is intended only to enable a party to receive back any charges which he may have paid to the collector, occasioned by the enforcement of the tax after the application for an abatement had been made. This appears from the fact that costs previously incurred are excepted from its operations. It confers only a right to reimbursement of money paid by the applicant as incidental to the payment of his tax, but does not authorize the recovery of a compensation in the form of costs for time and trouble in prosecuting the application for an abatement. As there is no other provision of law empowering the commissioners to allow costs, this part of their judgment was erroneous, and a writ of certiorari must issue to correct the error.