SOMERVILLE, J.
(1, 2) The first assignment of error is that the trial court erred in overruling the demurrers to pleas 3, 4, A and B. If any one of these pleas was not subject to the grounds specified as to it, the assignment of error cannot be sustained. Plea 3 — that defendant is not indebted to plaintiff in any sum whatever — though technically inapt in assumpsit, is in effect a plea of the general issue, and the only ground of demurrer thereto is that “it is no -more than the general issue.” There was manifestly no error in overruling such a demurrer, and it follows that the entire assignmént of error must fail. Moreover, the grounds of demurrer assigned to the other pleas are but general in character, and do not meet the requirements of the statute (Code, § 5340) as to the specification of defects apparent in the pleas, if there be any.
(3, 4) By way of replication to defendant’s plea of set-off, plaintiff pleaded that the claims therein mentioned had never *667been filed as claims against the estate of his intestate as required by Code, § 2589, and that more than 12 months had elapsed between the grant of letters and the beginning of this suit. As a rejoinder to this replication, defendant pleaded “that at the time said money was paid, which is here sought to be recovered back, the defendant’s claims were not then barred by the statute of nonclaim.” This was manifestly not a good rejoinder, because, as pointed out by the demurrer, it failed to show that defendant was lawfully entitled to demand the payment to her of the money claimed. So far as the preservation and enforcement of a specific lien upon an intestate’s property is concerned, it is certainly not necessary to file with the personal representative a claim for the debt which supports the lien. But in order to preserve the debt as a charge upon the intestate’s general estate, such a filing is necessary.—Duval v. McLoskey, 1 Ala. 708, 744, 745; Smith v. Gillam, 80 Ala. 296, 300. We think, therefore, that the trial court erred in overruling the demurrer to this rejoinder.
(5) It is patent, however, from the judgment entry, that the trial court did not find for the defendant on her plea of set-off, but only because, upon the evidence, the plaintiff was not entitled to recover the money claimed by him. We will not therefore reverse the judgment for this immaterial error.
The plaintiff’s testimony shows that, in the redemption by him, under the provisions of the mortgage, of certain platted parcels of the mortgaged land, he paid to the mortgagee, the defendant, $440 in excess of the amount required for that purpose by the terms of the mortgage; and he states that he paid this alleged excess under a mistaken interpretation of the language of the mortgage in its classification of values of separately redeemable lots. It appears that there was a good deal of argument and a full discussion between plaintiff and defendant’s attorney as to the amount that ought to be paid for the written release to be given by defendant of certain lots covered by the mortgage, and it appears from the mortgage itself that at the time this redemption was sought, June 3, 1915, a considerable sum of annual interest must have fallen due on the mortgage debt, besides the note for $2,000, which fell due. on March 10th preceding. The release recites that it is given “for and in consideration of the sum of $2,090 to me in hand paid,” etc., and stipulates that the money paid is to be applied on the mortgage *668debt. As to this, the defendant testifies that it was so applied, and it appears that all of the money was derived from the sale of the released lots.
(6, 7) It is of course well settled that money paid under a mistake of fact, though paid voluntarily, may be recovered in an action on the common counts.
But there are several exceptions to the rule, and it is generally held that such a payment cannot be recovered where the payer has derived a substantial benefit from the payment, nor where the payee received it in good faith in satisfaction of an equitable .claim. — 30 Cyc. 1316, 2, and cases cited. This would be especially true where, as here, the payment has furnished the specific inducement to some affirmative action by the payee, whether otherwise obligatory or not, whereby his situation has been unfavorably altered. These are matters of equitable rather than of legal cognizance, but general assumpsit for money had and received is an equitable action (P. & M. Ins. Co. v. Tunstall, 72 Ala. 142) and admits of equitable defenses.
(8) But, apart from these considerations, it seems to be a correct view of the law that a mistaken conclusion drawn by a party from the known terms of a contract is not a mistake of fact, but rather a mistake of law, and that money voluntarily paid in consequence of such a mistake cannot be recovered.—30 Cyc. 1318b, citing Cincinnati v. Cincinnati Gas, etc., Co., 53 Ohio St. 278, 41 N. E. 239.
Applying these principles to the evidence before the trial court, we think it was justified in rendering judgment for the defendant.
In view of the issues made by the pleadings, we think there was no prejudicial error in any of the rulings of the court on the evidence. Practically all of the questions propounded to plaintiff by his counsel which were at first excluded were after-wards answered fully by him; and the amount overdue on the mortgage at the time of the transaction in question was material to the issues. But the matters complained of would not, in any case, have controlled or directed the result.
The judgment will be affirmed.
Anderson, C. J., and Mayfield and Thomas, J.J., concur.