How to calculate tax amounts withheld on mixed pre-tax and Roth 401(k) contributions, and match?
When you adjust your investments the following will happen: Initial condition: Modified condition: This means that after this change you will note that the amount of federal tax you pay each month via withholding will go up. You are now contributing less pre-tax, so your taxable income has increased. If you make no other changes, then in April you will either have increased your refund by 6 months x the additional $25 a month, or decreased the amount you owe by the same amount. There is no change in the total 401K balance at the end of the year, other than accounting for how much is held pre-tax vs. Roth post-tax. Keep in mind that employer contributions must be pre-tax. The company could never guess what your tax situation is. They withhold money for taxes based on the form you fill out, but they have no idea of your family's tax situation. If you fail to have enough withheld, you pay the penalty — not the company. *The tax savings are complex because it depends on marital status, your other pre-tax amounts for medical, and how much income your spouse makes, plus your other income and deductions. Its easier than that: employer matching contributions are  always pre-tax. While your contribution is split between the pre-tax and the Roth post-tax parts, matching contributions are always pre-tax. Quote from the regulations I linked to: For example, matching contributions are not permitted to be allocated to a designated Roth account. So the tax you pay is only on the Roth portion of your contribution. One of the reasons for that is the complexity you're talking about, but not only. Matching is not always vested, and it would be hard to determine what portion to tax and at what rate if matching would be allowed to go to Roth. Your 401k IRA will now have three different sub-accounts, the one holding your Traditional (pre-tax) 401k contributions, the one holding your Roth 401k contributions, and the one holding the employer match contributions (which, as has been pointed out to you, cannot be considered to be Roth 401k contributions). That is, it is not true that So my next month's check shows $500+$500 going to the regular 401k, and $82+$82 going to the Roth 401k. Your next month's paystub will show $500 going into the regular 401k, $100 going into the Roth 401k, and if employer matching contributions are listed on the paystub, it will still show $600 going into the employer match. If you have chosen to invest your 401k in mutual funds (or stocks), shares are purchased when the 401k administrator receives the money and are also segregated in the three subaccounts. If you are paid monthly, then you will know on a month-by-month basis how many shares you hold in the three  separate subaccounts, and there is no end-of-year modification of how many shares were purchased with Roth 401k contributions versus how many were purchased with  pretax contributions or with employer matching funds as you seem to think.
I have a very hard time believing you pay 60% of gross. Otherwise, I believe you're right in the way this works: Suppose you make $100k and pay 25% of that in taxes. 100,000 * .25 = 25,000 But if you spend $1,000 pretax, then it's as if you were paid $99,000 99,000 * .25 = $24,750 So the difference is $250.  Which is the same as that $1,000 * .25. First, I believe that you can't just divide the losses over a number of years. I know that would be ideal as it might let you use the losses to only offset 25% income. A loss that gets you below zero taxable income would carry forward to the next year.  That said, I think it would be a great strategy to use the loss to offset a Roth conversion, in your case, from the traditional 401(k) to Roth 401(k). Keep in mind, as you've seen from using the 2016 tax year TurboTax, you should be able to make a fairly good estimate for your 2017 return. This could effectively use all of the loss to offset 25% income.  I'd look at the current projection and convert say 75-80% of the target amount immediately, then in November when the 2017 software comes out, convert the rest to get as close to your goal as you can. "The money you invested in your Roth was taxed as income when you filed your income tax.   A Roth contribution is ""post-tax"" as opposed to a standard IRA or 401k contribution which are ""pre-tax"". Pre-tax contributions lower your taxable income for the year. In example, you had income of $100,000 and made a standard IRA contribution of $5000. Your taxable income would be $95,000. In the case of a Roth contribution, the same $5000 investment would not reduce your taxable income for the year." "I humbly disagree with #2. the use of Roth or pre-tax IRA depends on your circumstance. With no match in the 401(k), I'd start with an IRA. If you have more than $5k to put in, then some 401(k) would be needed.  Edit - to add detail on Roth decision. I was invited to write a guest article ""Roth IRAs and your retirement income"" some time ago. In it, I discuss the large amount of pretax savings it takes to generate the income to put you in a high bracket in retirement. This analysis leads me to believe the risk of paying tax now only to find tHat you are in a lower bracket upon retiring is far greater than the opposite. I think if there were any generalization (I hate rules of thumb, they are utterly pick-apartable) to be made, it's that if you are in the 15% bracket or lower, go Roth. As your income puts you into 25%, go pretax. I believe this would apply to the bulk of investors, 80%+." I routinely max out my 401k contributions.  The company's stupid website actually forces me to make two contributions -- one for the regular contribution, and another for the Catchup Contribution. I routinely adjust my 401k contribution throughout the year -- at the first of the year, I calculate how much to withhold such that I can adjust withholding to 6% of salary more than before, once I hit the SS tax limit.  At the first of the year, I ignore bonuses.  I re-adjust (if needed) once I know bonuses. I've worked for my company for almost 30 years now. The amount you contribute will reduce the taxable income for each paycheck, but it won't impact the level of your social security and medicare taxes. A 401(k) plan is a qualified deferred compensation plan in which an   employee can elect to have the employer contribute a portion of his or   her cash wages to the plan on a pretax basis. Generally, these   deferred wages (commonly referred to as elective contributions) are   not subject to income tax withholding at the time of deferral, and   they are not reflected on your Form 1040 (PDF) since they were not   included in the taxable wages on your Form W-2 (PDF). However, they   are included as wages subject to withholding for social security and   Medicare taxes. In addition, employers must report the elective   contributions as wages subject to federal unemployment taxes. You might be able to keep this up for more than 7 weeks if the company offers health, dental and vision insurance. Your contributions for these policies would need to be paid for before you contribute to the 401K. Of course these items are also pre-tax so they will keep the taxable amount at zero. If there was a non-pretax deduction on your pay check that would keep the check at zero, but there would be taxes owed. This might be union dues, but it can also be some life and disability insurance polices. Most stubs specify which deductions are pre-tax, and which are post-tax. Warning. If you get the company match some companies give you the maximum match for those 7 weeks, then zero for the rest of the year. Others will still credit you with a match at the end of the year saying if you should get the benefit. It is not required that they do this. Check the company documents. You could also contribute post-tax money, which is different than Roth 401K, for the rest of the year to keep the match going. Note: If you are turning 50 this year, or are already 50, then you can contribute an additional $5,500 "I'd suggest you avoid the Roth for now and use pretax accounts to get the greatest return. I'd deposit to the 401(k), enough to get as much match as permitted, then use a traditional IRA. You should understand how tax brackets work, and aim to use pre-tax to the extent it helps you avoid the 25% rate. If any incremental deposit would be 15% money, use Roth for that. Most discussions of the pre-tax / post tax decision talk about 2 rates. That at the time of deposit and time of withdrawal. There are decades in between that shouldn't be ignored. If you have any life change, a marriage, child, home purchase, etc, there's a chance your marginal bracket drops back down to 15%. That's the time to convert to Roth, just enough to ""top off"" the 15% bracket.  Last, I wouldn't count on that pension, there's too much time until you retire to count on that income. Few people stay at one job long enough to collect on the promise of a pension that takes 30+ years to earn, and even if you did, there's the real chance the company cancels the plan long before you retire." Assuming that what you want to do is to counter the capital gains tax on the short term and long term gains, and that doing so will avoid any underpayment penalties, it is relatively simple to do so. Figure out the tax on the capital gains by determining your tax bracket. Lets say 25% short term and 15% long term or (0.25x7K) + (0.15*8K) or $2950.  If you donate to charities an additional amount of items or money to cover that tax. So taking the numbers in step 1 divide by the marginal tax rate $2950/0.25 or $11,800.  Money is easier to donate because you will be contributing enough value that the IRS may ask for proof of the value, and that proof needs to be gathered either before the donation is given or at the time the donation is given. Also don't wait until December 31st, if you miss the deadline and the donation is counted for next year, the purpose will have been missed. Now if the goal is just to avoid the underpayment penalty, you have two other options.  The safe harbor is the easiest of the two to determine. Look at last years tax form. Look for the amount of tax you paid last year. Not what was withheld, but what you actually paid. If all your withholding this year, is greater than 110% of the total tax from last year, you have reached the safe harbor. There are a few more twists depending on AGI Special rules for farmers, fishermen, and higher income taxpayers.   If at least two-thirds of your gross income for tax year 2014 or 2015   is from farming or fishing, substitute 662/3% for 90% in (2a) under   the General rule, earlier. If your AGI for 2014 was more than $150,000   ($75,000 if your filing status for 2015 is married filing a separate   return), substitute 110% for 100% in (2b) under General rule ,   earlier. See Figure 4-A and Publication 505, chapter 2 for more   information. First, the single worst reason to do anything is because most people are doing it. The second worst thing is to take tax advice from a non-tax pro. (Ironic, I understand, but read on) Run through your 2015 tax return. Do you itemize already? If not, there's a reason, the standard deduction for a couple is $12,600 in 2016, so a renter isn't likely to have enough deductions to itemize, even with a high state tax.  For 2016, project your total interest from the mortgage, and the year's property tax, then add your state income tax, and last, any charitable donations. This total comprises the bulk of what people take on their Schedule A. Now, since your current withholding assumes the standard $12,600, subtract this number, and you're left with the amount your taxable income will be reduced for the fact that you have the house. Last, divide this number by $4000. The result is how many more withholding allowances you can claim. One personal exemption (a withholding allowance) is exactly $4050 this year.  For what its worth, median home price for early 2016 was $190K. After 20% down, a $152K mortgage would cost about $6000 in interest the first year, and maybe $3000 in property tax. The average couple, making $60,000 or so won't have a state bill much over $3000, so shy of some nice donations, it's easy to have a house, yet still not itemize.  Of course, if you have higher income and a more expensive home, the numbers will be different.  The best you can do is to get tax software or use an online service and estimate the 2016 return based on your numbers. If you wish to post numbers via an edit to your question, I'm happy to update my answer a bit to your situation.  Note - the form you'll use to adjust withholdings, the W4, offers a worksheet to perform the calculation.  It asks in line 1 for your total itemized deductions, then subtract the standard deduction, then divide by $4050. Pretty much what I suggested above. You are correct that W-4s are very confusing for multiple income homes, and even more so if you change salary significantly during the year.  There are just too many variables in those situations to provide an effective, simple form. Unfortunately, the best way to get accurate withholdings is trial-and-error.  Try and estimate how much tax you'll have to pay for the year.  There are several calculators out there, but essentially you can take your gross income, subtract the standard exemptions for you and all dependents, subtract the standard deductions (or estimate your itemized deductions), and compute your tax based on the federal tax tables.  Then subtract any tax credits you may be eligible for. Then estimate your withholdings for the year by multiplying your current withholdings by the number of pay periods left, and adding your YTD withholdings.  If your total withholdings are higher than your estimated tax, add one or two exemptions to reduce your withholdings (and vice versa).   If all that sounds like a lot of work (which it is), at a minimum make sure you withhold as much tax as you paid last year.  That way you avoid any tax penalties, but might have a tax bill when you file.  If you want to be conservative and withhold a little extra that's fine - you might even end up with a refund when you file.  The good news is it doesn't have to be exact; any difference will determine what you pay (or what refund you get) when you file. Regarding #1: use the free online version of turbotax and start to play with the numbers for the different options for filing. It can make a difference, based on the imbalance between the couples income. Also filing married but separate can eleiminate some deductions/credits. Regarding #2: when you submit your taxes use the forecasting tool in turbotax to see if you should adjust your withholding. 2012 will be tricky because unless you changed your withholding in early 2011 to account for the change in status, your refund/owe number for 2011 will be unrelated to what will happen in 2012.  Make sure you meet the safe harbor requirements, enough withheld to equal the previous years tax. Joe Taxpayer tried to give you a formula regarding exemptions, here is another explanation: Each exemption is worth a percent of $3800. If you are in the 10% bracket that means it is worth $380 per year.  If you got a big refund or wrote a big check, adjust accordingly. Regarding #4: getting a match is great. Make sure you leave nothing on the table. Other than that it won't make a difference which one you pick.  Look at the funds available, investment types, expenses and go with the one that makes the most sense to maximize. Remember you are not getting interest on the 401Ks you are investing and getting returns. There is no way to know which investment fund will be better in 2012. "The ""Deferral"" for the 401k means that you're not collecting your pay immediately, but instead diverting it to a retirement account (Roth 401k in this case). This article defines deferral well: What is the difference between a regular 401(k) deferral (pre-tax) and a Roth 401(k) deferral?  Under either a regular 401(k) deferral or a Roth 401(k) deferral, you   make a deferral contribution by electing to set  aside part of your   pay (by either a certain percentage or a certain dollar amount).  For   a regular 401(k) deferral, the  taxable wages on your W-2 are reduced   by the deferral contribution; therefore, you pay less current income   tax.   However, you will eventually pay tax on these contributions and   earnings when the plan distributes the regular  401(k) deferrals and   earnings to you.  The result is that the tax on the regular 401(k)   deferrals and earnings is only  postponed.  A Roth 401(k) deferral is an after-tax contribution, which  means you   must pay current income tax on the deferral.   Since you have already   paid tax on the deferral, you won’t pay tax on it again when you   receive a distribution of  your Roth 401(k) deferral.  In addition, if   you satisfy cer tain distribution conditions, then you won’t have to   pay tax  on the earnings either.  This means  that the distribution of   the Roth 401(k) earnings can be tax free not just tax  postponed. Traditionally, this deferred compensation typically was directed to a 401k, but now that Roth 401k is another available option, deferred compensation can be directed there as well." The details of the 401(k) are critical to the decision. A high cost (the expenses charged within the) 401(k) - I would deposit only to the match, and I'd be sure to get the entire match offered. In which case, that $3000 might be good to have available if you start out with a tight budget.  Low cost 401(k) w/match - a no-brainer, deposit what you can afford. Roth 401(k) w/match - same rules for expenses apply, with the added note to use Roth when getting started and in a lower bracket.  Yes, it makes sense to have both.  You should note, depositing to the Roth now is riskless. The account, not the investment. If you decide next year you didn't want it, you can withdraw the deposit with no penalty or tax. Edit to respond to updated question - there are two pieces to the Roth deposit issue. The deposit itself, which puts the $3000 earned income into tax sheltered account, and the choice to invest. These two are sequential and you can take your time in between. I'm not sure what you mean by the dividend timing. In an IRA or 401(k) the dividend isn't taxed, so it's a non-issue. In a cash account, you might quickly have a small tax issue, but this doesn't come into the picture in the tax deferred accounts. After determining your potential savings rate, it is important to spend some time considering your retirement goals. In particular, do you want to live on the same amount of money you live on today? Maybe more? Less? Less: If you plan on living on less than today, I would maximize pre-tax contributions as a first priority (ie, 401k). In doing so, you opt to withdraw the money in the future at a lower marginal tax rate. If you have other pre-tax accounts available, such as an HSA, I think it makes sense to go this route: The Same/More: If you plan on living on the same or more than today, then the Roth choice becomes a matter of personal preference if you believe taxes will be higher at retirement then today. For those in this camp, I've seen recommendations that say Roth should be approximately one-fifth to one-half of annual contributions (where possible). My suggestion would be to wager on the lower end as most pre-tax accounts can be converted to Roth in a year when you may be in a lower marginal tax bracket. Assuming your savings rate is 20% on 100k income, the one-fifth recommendation would be $4000 towards Roth and the other $16000 towards pre-tax accounts, such as 401k or HSA. On the statement it now tracks how much is contributed to the account   pre and post tax. This is the key. Your withdrawals will be proportional. Assuming you have contributed 90% in regular contributions (pre-tax) and 10% in Roth (post tax), when you withdraw $1000, it will be $900 from the regular (taxed fully) and $100 from the Roth (not taxed, assuming its a qualified distribution). Earnings attributed proportionally to the contributions. I agree with you that it is not the best option, and would also prefer separate accounts, but with 401k - the account is per employee. Instead of doing 401k Roth/Non-Roth consider switching to Regular 401k and Roth IRA - then you can separate the funds easily as you wish.