If your role hasn't changed and you've always been second to the CEO, it seems unlikely they are going to be able to offer big jump. Keep in mind most merit races are about 3%. Asking for something more is an option if the company has particularly strong financial foothold right now, but it's definitely not going to bring you up to market rate. I would also look a little deeper into the average - Is that average for the same job in the same area you live or national? National averages are often driven up by the highly urban areas.

I was in your position earlier this year and agree with Jennifer's advice. I used an email that was sent company-wide about setting employee's goals to preempt my discussion. I put together a bullet point list of my contribution that raised awareness, revenue or were additional to my job description. I told my manager that I would like to set a meeting to discuss and he agreed. After the meeting, a waiting game commenced and I didn't hear back. I was kicking myself for requesting the raise even though I had taken on a lot of extra responsibilities including management of a junior employee this year. I used another company email that said all changes were due to company documents to follow up with my manager and that action resulted that was finalized in the next quarter. I found that you have to be persistent while professional to go after what you want. Due to the pandemic, I had to wait until the next quarter to receive the raise due to budgetary matters but my persistence paid off and I'm glad I fought for the increase. Good luck!

Before you bring up a raise to your boss, I would do three things: 1. I would check out the company's finances to see if such a salary for you is actually sustainable. Since your company is a startup, it might not be on a sufficiently solid financial footing that it can afford to pay you much more, if at all, than it already is. 2. Quantify in writing how your contributions to the company affect its bottom line. If you can demonstrate that what you specifically do for the company has brought in more business, reduced costs, or otherwise improved its profitability, then you can make a better case for yourself that you deserve a raise. 3. I would be prepared to meet resistance to your request. The company may claim, even after you present documentation that you should receive a raise, that you haven't "earned" it, the company can't afford it, or that it wants you to jump through more hoops before it grants you a raise. I would conduct a preliminary job search just in case.