The steps of cell division happen in precise sequence, even though late processes often don’t inherently require successful completion of preceding ones. In the final stage of division, for example, cells are cut into separate entities by strictly ordered morphological rearrangements of cytokinesis and abscission. It’s not clear how cells enforce the exact sequence of these events. In budding yeast cell separation actomyosin ring contraction is closely coordinated with synthesis of a septum that’s immediately degraded once it’s completed. How do cells avoid destroying the septum before it’s finished? We find that cytokinetic mutants that significantly delay septum formation are highly sensitive to overproduction of the cell separation chitinase Cts1 and are suppressed by cts1, indicating that proper control of the cell separation program is critical when septum formation is defective. A signaling system called the RAM network links CTS1 transcription to mitotic exit. However, we find that transcription of septum destruction genes turns on just before actomyosin ring contraction, and that cells with defective septum synthesis produce the chitinase protein with normal timing but don’t secrete it. The dependency of cell separation enzyme secretion on completion of cytokinesis requires Fir1, a largely intrinsically disordered substrate of the RAM network kinase Cbk1. Deletion of FIR1 eliminates Cts1 secretion delay in cytokinesis mutants, which exhibit strong negative genetic interaction with fir1. While the RAM network isn’t required for anterograde membrane trafficking during growth, Cbk1 promotes secretion of chitinase. Fir1 inhibits this Cbk1 function as well as other aspects of post-cytokinesis secretion. Fir1 is normally quickly degraded during cell separation, disappearing from the cytokinesis site after actomyosin ring contraction, but is stabilized when septum formation is abnormal. Thus, an unknown mechanism links Fir1’s inhibition of septum destruction enzyme delivery to status of septum formation. Eukaryotes have evolved checkpoint systems that actively block late processes until preceding ones are complete, enforcing dependencies among otherwise mechanistically independent cell cycle events. We propose that a novel checkpoint protects the integrity of cytokinesis by blocking irreversible late steps until the process’s early stages are finished, and that Fir1 is a key part of this checkpoint in budding yeast.