How do I figure out what my taxes will be?

[lbonga1]

I am starting a new job on Monday, and I am trying to figure out what my taxes will be. Basically what I'm trying to do is contribute enough to my 401k to get my tax liability to zero, then put the rest of my paycheck (beyond expenses) into my Roth IRA and/or savings for our house downpayment.

According to the w-4 worksheet, I should be claiming 7. My salary will be $45k. I also work as an independent contractor for a different company and have been averaging $2k/month income, but this will likely go down once I start my new job. Taxes are not withheld by the company I do the independent contracting for. I file as HoH, 2 dependents but no childcare expenses, and I will be in school half-time starting in Fall. I live in CA, so there's state income tax too.
My new employer does not match any 401k contributions, and I'm not sure yet what the fund options are. My Roth IRA is a rollover from a 401k with a previous employer and was worth ~$9k at the time of the rollover (rolled over in 2016), so I'll have to take that into consideration for the 2016 tax year too. It is 100% in VTSMX, but I'm about to throw a few hundred in there to switch to VTSAX.

Can anyone guide me in accomplishing this? Let me know if I've left anything important out.

[MDM]

I am starting a new job on Monday, and I am trying to figure out what my taxes will be. Basically what I'm trying to do is contribute enough to my 401k to get my tax liability to zero, then put the rest of my paycheck (beyond expenses) into my Roth IRA and/or savings for our house downpayment.

According to the w-4 worksheet, I should be claiming 7. My salary will be $45k. I also work as an independent contractor for a different company and have been averaging $2k/month income, but this will likely go down once I start my new job. Taxes are not withheld by the company I do the independent contracting for. I file as HoH, 2 dependents but no childcare expenses, and I will be in school half-time starting in Fall. I live in CA, so there's state income tax too.
My new employer does not match any 401k contributions, and I'm not sure yet what the fund options are. My Roth IRA is a rollover from a 401k with a previous employer and was worth ~$9k at the time of the rollover (rolled over in 2016), so I'll have to take that into consideration for the 2016 tax year too. It is 100% in VTSMX, but I'm about to throw a few hundred in there to switch to VTSAX.

Can anyone guide me in accomplishing this? Let me know if I've left anything important out.

You have just done your 2015 taxes, correct?  Unless you threw everything over the wall to a CPA and received only "here is what you owe" in return, you are all set to estimate 2016 taxes.  "Do" a 2016 return by changing the 2015 entries to what you expect for 2016, and there you go.  It won't be exact (tax brackets, etc., will change), but for practical purposes it will be an estimate as good as the inputs you provide.

If that answer isn't specific enough (and it might not be), just ask about the unclear part(s).

See also http://forum.mrmoneymustache.com/taxes/best-way-to-calculate-w-4-exemptions-for-2016/ and http://forum.mrmoneymustache.com/taxes/am-i-witholding-too-much/ for similar discussions.

[lbonga1]

Well, my 2015 taxes were on the unusual side. I was on unemployment for 6 months, and worked as an independent contractor without any taxes withheld for the remainder of the year. I still received a $7k refund, solely due to credits that I qualified for. I can imagine this year won't be like that.

This year was my first year doing my taxes by myself, so I think I just don't know enough about personal exemptions, deductions, etc. I just used Turbo Tax and entered in whatever values it asked me for.

[Ursus Major]

This year was my first year doing my taxes by myself, so I think I just don't know enough about personal exemptions, deductions, etc. I just used Turbo Tax and entered in whatever values it asked me for.

Since you have TurboTax, you just follow the previously given advice and enter your 2016 tax situation into the program (as a new tax return). This will give you a reasonably good estimate.

[NoStacheOhio]

Did you roll a traditional 401k into a Roth IRA? If so, that conversion is going to be taxable. You may end up depositing or recharacterizing to a tIRA when you do your taxes to eliminate liability in 2016.