A close result will not be enough to trigger a repeat count, officials say.
Only concerns about the integrity of the process in the 32 counting areas will be considered a sufficient reason.
The warning comes from Mary Pitcaithly, the chief counting officer for the referendum.
Both sides are hoping for a clear and definitive result on the morning of September 19.
But historical parallels suggest that that may not happen.
In the Quebec independence referendum in 1995, the No side won with 50.6 per cent of the vote, compared to the Yes side on 49.4 per cent.
The Scottish Independence Referendum Act 2013 also states that votes cannot be recounted after a final result has been declared.
Ms Pitcaithly said: "When I declare the result … I will do so with confidence, however close it may be, because I will have confidence in the 32 totals that comprise the result."