How about a lottery win - or a gambling gain? True. (Interestingly, Jersey law is similar to UK law in one important respect with regard to gambling: gambling "contracts" are unenforceable in Jersey's Courts. So if you have a wager with a friend and the friend does not pay, Jersey's courts will not make him pay.)
But a lottery win or a gambling gain is, in a way, a “due”…. admittedly from a very small outlay.
Can there ever be a credit, an accounting entry, a deposit on the plus side, for any individual - without any previous outlay?
Righteousness can be credited without any outlay whatsoever on the part of the person to whom it is credited.
In these really distressing days for very many folk in Jersey regarding past sexual sins - and past cover-ups of sexual sins - this may be a most welcome truth to discover. Almighty God (and Jesus Christ his Son, the Judge of all) credits righteousness to a person without the person working at all. It is counted to him not as a "due" but as a gift.
As if to confirm this beyond any doubt whatsoever for any person whose sexual sins and subsequent actions loom large in his past, Paul continues his above sentence by reminding his readers in Rome about King David (alive 990 BC) who brought into his bed another man's wife. She became pregnant. David tried to cover it up by getting the husband to come back on army leave - but he didn't sleep with his wife. So David had him placed in a disastrous position near enemy lines and the husband was killed.