re: Quarterly taxes

It depends on your marginal income tax rate but I think 25% is a good figure to start off with. Since this is a side job have you considered having more taxes withheld from your regular job pay? I am retired now but when I was working a full time job and some as an independent contractor, I did this. I avoided having to file quarterly and still managed to owe the IRS a small amount almost every year at filing time. Even though I owed them a small amount I was never forced to pay quarterly. My tax professional helped my wife and me with this.