This offer isn't fair, and you already know it. A 20 percent drop below a posted salary range, paired with a contract structure that shifts tax, benefits, and security risk entirely onto you, is not a negotiation, it's a signal. Early-stage startups often operate on tight budgets, but that doesn't excuse misrepresenting compensation in a job posting. You did the right thing by pushing back and asking for a full-time probation period. That request is reasonable and standard. Their response will tell you everything about whether they value your expertise or simply need someone willing to absorb the downside.
Your concern about time and energy is the real issue here. A three-month contract at an early-stage company, especially one that already undervalues you, will demand everything you have. You are right to worry that you won't have room to keep interviewing or preparing for other roles. The math is unforgiving: if you take this offer as-is, you trade three months of active search for a contract that might not convert. You could end up back where you started, with less runway and no backup plan. The idea that you can renegotiate from a stronger position later is tempting, but it rarely works when the starting point is below the floor. That gap sets a precedent, not a launchpad.
You bring a master's degree, publications, and five to six years of combined research and industry experience. That is not a profile that should accept below-range pay with no benefits. The market is tough right now, but one offer does not mean you have to take every offer. Holding out for something cleaner and more stable is not stubbornness, it's protecting the value of your own time and skill set. You stepped away from your last role because the environment changed and burned you out. Don't trade one uncertain situation for another that pays less.
Wait for their answer on the full-time probation structure. If they come back with a genuine adjustment to the salary and terms, then you have a real decision to make. If they hold firm or offer only a token increase, you have your answer: this is not a partnership that respects what you bring. Walk away and keep searching. The right role will align the work, the compensation, and the structure, not ask you to choose between them.