Texas Local Government Code - LOC GOV'T § 43.055. Maximum Amount of Annexation Each Year

(a) In a calendar year, a municipality may not annex a total area greater than 10 percent of the incorporated area of the municipality as of January 1 of that year, plus any amount of area carried over to that year under Subsection (b). In determining the total area annexed in a calendar year, an area annexed for limited purposes is included, but an annexed area is not included if it is:

(b) If a municipality fails to annex in a calendar year the entire 10 percent amount permitted under Subsection (a), the municipality may carry over the unused allocation for use in subsequent calendar years.

(c) A municipality carrying over an allocation may not annex in a calendar year a total area greater than 30 percent of the incorporated area of the municipality as of January 1 of that year.