Seats for board President Renae Mitchell, Place 3; Vernagene Mott, Place 4; and Brian Allen, Place 5 expire this May.
The filing window will remain open to potential school board candidates through Feb. 18 at 5 p.m.
Applications to run for the PfISD school board are available on the district's website.
The last day to declare write-in candidacy will be Feb. 22 before 5 p.m.
PfISD members serve staggered, three-year terms. There will not be any elections for the city of Pflugerville in May.