Short answer. You start from zero. Article 1121 provides that possession is naturally interrupted once it ceases for more than one year, and if you resume possession afterward, the old possession is not revived. Your later occupation begins a fresh count for prescription purposes, separate from whatever period had accrued before the interruption.
What the law says
Possession is naturally interrupted when through any cause it should cease for more than one year. The old possession is not revived if a new possession should be exercised by the same adverse claimant.
Civil Code, Article 1121 — Natural Interruption. Read the full provision →
When possession is naturally interrupted
Article 1121 sets a specific threshold for when possession is considered naturally interrupted: possession is naturally interrupted when through any cause it should cease for more than one year. If you stopped occupying the land and stayed away for longer than a year, that gap is enough, under this article, to count as a natural interruption of your possession, regardless of the particular reason you stopped occupying it.
Why the old possession isn't revived
Having established that the interruption occurred, the article then addresses exactly your situation — what happens when possession resumes afterward. It states plainly that the old possession is not revived if a new possession should be exercised by the same adverse claimant. In other words, moving back onto the land does not reach back and reconnect to the possession you had before the year-long gap; the earlier period is simply not brought back to life by resuming occupation later.
What 'the same adverse claimant' means here
The phrase 'the same adverse claimant' matters because it identifies whose possession the rule is talking about — yours, as the person who occupied the land both before and after the interruption. The article is not concerned with a different person taking over possession; it addresses the specific scenario where the same individual who once possessed the property leaves it for over a year and then returns to possess it again.
The practical effect: starting the count over
The practical result follows directly from the two rules together: because the earlier possession is naturally interrupted after a year's absence, and because that old possession is not revived by your later return, your new occupation stands on its own. Any prescriptive period you are trying to build now runs from when you moved back in, not from where the earlier, interrupted period left off before you stopped occupying the land.
What the article doesn't give you
Article 1121 grants no partial credit for the time you possessed the land before the gap, and it does not distinguish between leaving voluntarily and being kept away for reasons outside your control — the one-year threshold and the same-claimant rule apply either way, since the article ties itself to the cause being 'any cause' at all. Its text also does not address a separate scenario: a third party taking over possession during your absence, rather than you simply resuming it yourself, which is not the situation this particular article speaks to.