CRW:
Anyone who is aware of having committed a mortal sin must not receive Holy Communion, even if he experiences deep contrition, without first received sacramental absolution, unless he has a grave reason for receiving Communion and there is no possibility of going to confession.
Thomas sets up a case in point for the latter part of your preceding paragraph, and this is where you will find the exception for the one year allowance.
Italics Summa
I answer that, As the purpose of confessing is united to contrition, a man is bound to have this purpose when he is bound to have contrition, viz. when he calls his sins to mind, and chiefly when he is in danger of death, or when he is so circumstanced that unless his sin be forgiven, he must fall into another sin: for instance, if a priest be bound to say Mass, and a confessor is at hand, he is bound to confess or, if there be no confessor, he is bound at least to contrition and to have the purpose of confessing.
The first accidental case is where it applies. The implication is that it applies for pressing cases where he cannot do without committing a mortal sin, and the case here is given for the reception of the Eucharist. This seems reasonable, has it would seem he deserves a token dispensation due to the individual’s precarious position.
*But to actual confession a man is bound in two ways.
**
First, accidentally, viz.
when he is bound to do something which he cannot do without committing a mortal sin, unless he go to confession first: for then he is bound to confess; for instance, if he has to receive the Eucharist, to which no one can approach, after committing a mortal sin, without confessing first, if a priest be at hand, and there be no urgent necessity.
Hence it is that the Church obliges all to confess once a year; because she commands all to receive Holy Communion once a year, viz. at Easter, wherefore all must go to confession before that time.
*The next paragraph leaves the exceptional cases behind and deals primarily with instilling urgency of confession.
*Secondly, a man is bound absolutely to go to confession; and here the same reason applies to delay of confession as to delay of Baptism, because both are necessary sacraments. Now a man is not bound to receive Baptism as soon as he makes up his mind to be baptized; and so he would not sin mortally, if he were not baptized at once: nor is there any fixed time beyond which, if he defer Baptism, he would incur a mortal sin. Nevertheless the delay of Baptism may amount to a mortal sin, or it may not, and this depends on the cause of the delay, since, as the
Philosopher says (Phys. viii, text. 15), the will does not defer doing what it wills to do, except for a reasonable cause. Wherefore if the cause of the delay of Baptism has a mortal sin connected with it, e.g. if a man put off being baptized through contempt, or some like motive, the delay will be a mortal sin, but otherwise not: and the same seems to apply to confession which is not more necessary than Baptism.
Moreover, since man is bound to fulfill in this life those things that are necessary for salvation, therefore, if he be in danger of death, he is bound, even absolutely, then and there to make his confession or to receive Baptism. For this reason too, James proclaimed at the same time the commandment about making confession and that about receiving Extreme Unction (
James 5:14,16). Therefore the opinion seems probable of those who say that a man is not bound to confess at once, though it is dangerous to delay.
*
The correct way to read 1457 then is that once a year a confession is cumpulsory, disposition irrelevant, not that an individual has a year to confess his mortal sin.
AndyF