An I am Employee or a Partner? (Co-Founder)

I co-founded a business several months ago with one other co-founder. He's the CEO and invested all of the capital. At the beginning of the company I signed an employment agreement that outlined my job title (CTO) and my yearly salary. I also have significant equity that vests over time. However, he states since I am a cofounder that I am technically a partner, and as long as he stops paying employment taxes and gives me my salary without anything withheld that I would then be considered a partner. I know there are nuances to the "How much decision making power you have" along with risk and what not, but are there any hard and fast identifiers that make you a partner instead of an employee? From what I can tell, even though I thought I was a co-founder, I am technically (for tax purposes) an employee because I signed the employment agreement and had my salary set on that agreement.