However, the following are not deductible:
1° Debts which fell due more than three months before the opening of the succession, unless a certificate is produced by the creditor certifying their existence at that time, in the form and according to the rules determined in article L. 20 of the Book of Tax Procedures;
2° Debts granted by the deceased in favour of his heirs or interposed persons. The persons designated in the last paragraph of Article 911 of the Civil Code are deemed to be interposed persons.
However, where the debt was granted by an authenticated deed or by a private deed with a date certain before the opening of the succession other than by the death of one of the contracting parties, the heirs, donees and legatees, and persons deemed to be interposed have the right to prove the sincerity of this debt and its existence on the day of the opening of the succession ;
3° Debts recognised by will;
4° Mortgage debts guaranteed by a registration that has lapsed for more than three months, unless the debt is not due and its existence is certified by the creditor in the forms provided for in article L. 20 of the Book of Tax Procedures; if the registration has not lapsed, but if the figure has been reduced, only the excess shall be deducted, if applicable;
5° Debts in capital and interest for which the limitation period has expired, unless it can be justified that the limitation period has been interrupted.