The spring equinox is always the same - March 21st. Maybe it can happen astronomically just after midnight, so technically the 22nd? But it all depends on whether a full moon has just happened the day (or seconds?) before the equinox, and you have to wait 28 days for the next one, or it happens just after. And then whether that happens on the Saturday, so the very next day is Easter Sunday, or a Monday, and you have to wait another week.

Fun with almanacs and 6th-century clergy!