A SBA size protest related to a sealed bid must be filed within five business days of bid opening–and the bid protest rules under FAR Part 33 do not provide for a longer protest window.
In a recent decision, the SBA Office of Hearings and Appeals confirmed that, when it comes to size protests, the timeliness rules for bid protests (which allow many protests to be filed within 10 days after the basis of protest was known or should have been known) simply do not apply.