Revisional Round UPSC relevant
The revisional round is the short mop-up visit after the main enumeration period that updates the count to the census moment.
Enumerators revisit their blocks to record births, deaths and moves that occurred between their earlier visit and 00:00 hrs of the reference date, and to enumerate visitors not counted elsewhere. In Census 2011 the population enumeration ran February 9–28, 2011 and the revisional round from March 1 to 5, 2011, aligning everything to 00:00 hrs of March 1, 2011. Census 2027 is expected to follow the same architecture around its March 1, 2027 reference moment (exact PE and revisional dates for the main phase were still to be notified in detail as of August 2026).
The revisional round is what makes an 'extended' de facto census statistically equivalent to a one-moment count.