I can build you a multi million dollar website single handedly; build you a server farm, install and configure a PBX - but I can't for the life of me get accounting down or keep my stuff strait I have 2 jobs - day job is a regular every day paycheck with W4 and government taxes taken out per check, every 2 weeks 2nd job is my startup - I get paid once a month; no taxes taken out and I file as a contractor at the end of the year. The 2nd job kills me - at the end of the year I end up owing in excess of 20k. We do not have the financial savings ethic to send the government a check every 3 months for $5000 as we've been instructed to do so since I started getting paid from my startup. It's just not us. So we pay it in 4 payments after tax season (now) Assuming everything stays the same; startup keeps making money; I keep getting paid - I do not want to owe again next year So - I have 2 options that I know of (if anyone else has an idea; I'm all ears) option 1 - max out my 401k contribution at day job - having another $461 taken out of each paycheck option 2 - re-file my W4 at the day job and have them take out an additional $500 / paycheck None of these are fun obviously - who the hell wants to take a $500 / paycheck pay cut - but if it means I owe less next year... Assuming the 401k contribution is pre-tax now (I know I'll be taxed on it when I use it) - are these 2 options equal? Obviously, it's a better idea to pay myself then send it to the government. But if I put another $461 on the 401k every 2 weeks and I still owe 10k+ next year, I'll be pissed... Not looking to get a refund, just looking to get as close to $0 owed as possible next year.