Yes, per the SEC website: "You can calculate your annual income or net worth by jointly including your spouse’s income or assets.  It is not necessary that property be held jointly.  However, if you do calculate your income or assets jointly with your spouse, each of your crowdfunding investments together cannot exceed the limit that would apply to an individual investor at that annual income or net worth level."

Net Worth is all of your assets minus liabilities, not including your primary residence (home) and mortgage. Check out Republic.co's Net Worth example here

The rules that the calculator uses are based on the SEC guidance here. You can also download a copy of the spreadsheet version of the tool to gain a better understanding of how the inputs determine your 12-month number.