Why ADP does not accurately withhold state and federal income tax (even if W4 is correct)?
ADP does not know your full tax situation and while the standard exemption system (actually designed by the IRS not ADP) works fairly well for most people it is an approximation.  This system is designed so most people will end up with a small refund while some people will end up owing small amounts.  So, while it is possible that ADP has messed up the calculations it is unlikely this is the cause.  The most likely cause is that approximation ends ups making you pay less tax during the year than you actually owe. A few people like your friend may end up owing large amounts due to various circumstances.  It is always your responsibility to make sure you pay enough tax throughout the year.  While this technically means that you need to do your taxes every quarter during the year to make sure you pay the correct tax during the year, for most people this ends up being unnecessary as the approximation works fine.  It is possible the exemption system failed your friend, but much more commonly people owe penalties because they put the wrong number of exemptions or had other side income. On a related note, most people in finance would argue that your situation where you owe some money at tax time, but not so much that you have to pay a penalty, is actually the best way to go.  Getting a tax refund actually means you paid more tax than you needed to.  This is similar to giving an interest-free loan to the government. I see several interesting statement in your question.  A. my only income is from my Employer B. I also receive employer stock (ESPP, RSU, NSO). However, employer withholds taxes for these stock transactions through my broker (I see them broken down on my W2).  C. I have been subject to Alternative Minimum Tax. A implies a simple tax return. B and C tell the opposite story. In fact if B is not done correctly The amount withheld due to payroll may be perfect but the under withholding could be due to the ESPP's, RSUs and NSOs.  The AMT can throw everything else out the window.  If a person has a very simple tax situation: Income doesn't change a lot from paycheck to paycheck; they take the standard deduction; the number of exemptions equals the number of people in the family. Then the withholding is very close to perfect.  The role of the exemptions on the W-4 is to compensate for situations that go above the standard deduction. The role of extra withholding is when the situation requires more withholding due to situations that will bring in extra income or if the AMT is involved.
"Yep. You're single, you're possibly still a dependent on your parent's taxes (in lieu of rent), and you're finally bringing home bacon instead of bacon bits. Welcome to the working world. Let's say your gross salary is the U.S. median of $50,000. With bi-weekly checks (26 a year; common practice) you're getting $1923.08 per paycheck. In the 2013 ""Percentage Method"" tax tables, here's how your federal withholding is calculated as a single person paid biweekly: Federal taxes are computed piecewise; the amount up to A is taxed at X%, then the amount between A and B is taxed at Y%, so if you make $C, between A and B, the tax is (A*X) + (C-A)*Y. The amount A*X is included in the ""base amount"" for ease of calculation. Back to our example; let's say you're getting $1923.08 gross wages per check. That puts you in the 25% marginal bracket. You pay the sum of all lesser brackets (which is the ""base amount"" of the 25% bracket), plus the 25% marginal rate on every dollar that falls within the bracket. That's 191.95 + (1923.08 - 1479) * .25 = 191.95 + (444.08 * .25) = 191.95 + 111.02 = $302.97 per paycheck. The ""effective"" tax rate on the total amount, as if you were being charged a flat tax, is 15.75%, and this is just for the federal income tax. Add to this MA state income taxes (5.25% flat tax), FICA (aka Medicare; 1.45% flat) and SECA (aka Social Security; 6.2% up to a ""wage base"" that $50k doesn't even approach), and your effective tax rate on each dollar you earn is 15.75% + 5.25% + 1.45% + 6.2% = 28.65%. This doesn't include any state unemployment taxes that may be withheld separately, but as the rate I come up with is pretty darn close to what you've figured (meaning I slightly overestimated your gross income and thus your effective tax rate), my bet is that SUTA's either employer-paid in MA, or it's just part of MA state income tax. It gets better, at least at the federal level: The amount of your state income taxes is tax-deductible at the federal level if you itemize your deductions. That may not be a factor for you as you'd have to come up with more than $6,100 of other tax-deductible expenses to make itemizing the better option than taking the standard deduction (big-ticket items are mortgage expenses other than principal payments, hospital stays such as for childbirth or major accident, and state and local taxes such as sales, property and income). If you can claim yourself as a dependent (meaning your parents can't), then $150 of each check ($3,900 of your annual salary) is no longer taxed for federal withholding, lowering the amount of money taxed at the 25% marginal rate. You effectively save $37.50 biweekly ($975 annually) in taxes. Get married and file jointly, and your spouse, her personal exemption, and an extra standard deduction amount (if you don't itemize) go on your taxes. The tax rates for married couples filing jointly are also lower; they're currently calculated (or were in 2012) to be the same as if two equal earners were to file separately, so if your spouse doesn't work, your taxes on the single income are calculated at the rates you'd get if you earned half as much. It doesn't work out to half the taxes, but it is a significant ""marriage advantage"". Have kids, and each one is another little $3,900 tax write-off. It's nowhere near the cost of having or raising the child, but it helps, and having kids isn't about the money. Owning a home, making charitable deductions, having medical expenses, etc are a toss-up. The magic number in 2013 is $12,200 for a married couple, $6,100 for a single person. If your mortgage interest, insurance premiums, property taxes, medical expenditures, charitable donations, any contributions from your take-home pay to a tax-deferred savings account (typically these accounts are paid into by your employer as a ""pre-tax deduction"" and never show up as taxable income, but you could just as easily move money from your take-home pay into tax-deferred savings) and any other tax-deductible payments add up to more than 12 large, then itemize. If not, take your standard deduction. As a single taxpayer just starting out in life, you probably don't have any of these types of expenditures, certainly not enough to give up the SD. I did the math on my own taxes in 2012, and was surprised at how little the government actually gets of my paycheck when all's said and done. Remember back in the summer of 2012 when everyone was mad at Romney for making millions and only paying an effective income tax rate of 14%, which was compared to the middle class's marginal rate of 25-28%? Well, my family of 3, living on a little more than the median income from one earner (me), taking the married standard deduction, three personal exemptions, and a little extra for student loan interest, paid an effective federal income tax rate of something like 3.5%. Of course, the FICA and SS taxes don't allow any deductions (not even for retirement savings), so add in the 4.2% SS (in 2012) and 1.45% FICA and the full federal gimme was more like 9-10%." "1 - in most cases, the difference between filing joint or married filing single is close to zero. When there is a difference you're better off filing joint.  2 - The way the W4 works is based on how many allowances you claim. Unfortunately, even in the day of computers, it does not allow for a simple ""well my deduction are $xxx, don't tax that money."" Each allowance is equal to one exemption, same as you get for being you, same as the wife gets, same as each kid. 3 people X $3800 = $11,400 you are telling the employer to take off the top before calculating your tax. She does this by using Circular E and is able to calculate your tax as you request. If one is in the 15% bracket, one more exemption changes the tax withheld by $570. So if you were going to owe $400 in April, one few exemption will have you overpay $170. i.e. in this 15% bracket, each exemption changes annual withholding by that $570.  For most people, running the W4 numbers will get them very close, and only if they are getting back or owing over $500, will they even think of adjusting.  3 - My recently published Last Minute Tax Moves offers a number of interesting ideas to address this. The concept of grouping deductions in odd years is worth noting.  4 - I'm not sure what this means, 2 accounts each worth $5000 should grow at the same rate if invested the same. The time it makes sense to load one person's account first is if they have better matching. You say you are not sure what percent your wife's company matches. You need to change this. For both of your retirement plans you need to know every detail, exact way to maximize matching, expense ratios for the investments you choose, any other fees, etc. Knowledge is power, and all that. In What is an appropriate level of 401k fees or expenses in a typical plan? I go on to preach about how fees can wipe out any tax benefit over time. For any new investor, my first warning is always to understand what you are getting into. If you can't explain it to a friend, you shouldn't be in it.  Edit - you first need to understand what choices are within the accounts. The 4% and 6% are in hindsight, right? These are not fixed returns. You should look at the choices and more heavily fund the account with the better selection. Deposit to her account at least to grab the match.  As far as the longer term goals, see how the house purchase goes. Life has a way of sending you two kids and forcing you to tighten the budget. You may have other ideas in three years. (I have no P2P lending experience, by the way.)  Last - many advise that separate finances are a bad path for a couple. It depends. Jane and I have separate check books, and every paycheck just keep enough to write small checks without worry, most of the money goes to the house account. Whatever works for you is what you should do. We've been happily married for most of the 17 years we've been married." Your question begins with a misunderstanding.  When you prepare your tax return (Form 1040/1040A/1040EZ) you always try to minimize your total tax bill.  When you fill out form W4 you trying to estimate how much tax will be shown on next years tax return.  The penalty for having too much tax withheld is not having the use of the money until you get a tax refund. At the moment interest rates are very low and your economic loss is the temporary loss of access to the money. One exception would be if you are carrying credit card debt. In that case you are, in effect, paying 20-30% interest to borrow money you lending to the US Treasury for 0% interest. The penalty for having too little tax withheld is having to make a large payment with your tax return. If your pre-payments aren't at least as much as your total income tax from last year there may also be modest underpayment penalty based on the difference between your pre-payments and your total income tax from last year or this year whichever is less. A large underpayment will trigger a different larger underpayemnt penalty. The W4 combined with the withholding rates tends to over-withhold income tax for most, but not all, taxpayers. Most people don't have enough savings to pay a large tax due, which leads to more penalties and an even larger bill. Over-witholding protects the overall tax system from the consequences of those events. People tend to be very unhappy, not quietly. On balance your greatest economic benefit depends on whether or not you have high interest debt. If you do, then accurate and even slightly under-withholding will probably work to your advantage as long as you can pay next 4/15. If not, avoiding the chance of having any unexpected balance due next year may be more important. When you itemize your deductions, you get to deduct all the state income tax that was taken out of your paycheck last year (not how much was owed, but how much was withheld). If you deducted this last year, then you need to add in any amount that you received in state income tax refunds last year to your taxes this year, to make up for the fact that you ended up deducting more state income tax than was really due to the state.  If you took the standard deduction last year instead of itemizing, then you didn't deduct your state income tax withholding last year and you don't need to claim your refund as income this year. Also, if you itemized, but chose to take the state sales tax deduction instead of the state income tax deduction, you also don't need to add in the refund as income.  For whatever reason, Illinois decided that you don't get a 1099-G. It might be that the amount of the refund was too small to warrant the paperwork. It might be that they screwed up. But if you deducted your state income tax withholding on last year's tax return, then you need to add the state tax refund you got last year on line 10 of this year's 1040, whether or not the state issued you a form or not.  Take a look at the Line 10 instructions  starting on page 22 of the 1040 instructions to see if you have any unusual situations covered there that you didn't mention here. (For example, if you received a refund check for multiple years last year.) Then check your tax return from last year to verify that you deducted your state income tax withholding on Schedule A. If you did, then this year add the refund you got from the state to line 10 of this year's 1040. This question came up again (Living in Florida working remotely - NY employer withholds NYS taxes - Correct or Incorrect?) and the poster on the new version didn't find the existing answers to be adequate, so I'm adding a new answer.   NYS will tax this income if the arrangement is for the convenience of the employee. If the arrangement is necessary to complete the work, then you should have no NYS tax. New York state taxes all New York-source salary and wage income of nonresident employees when the arrangement is for convenience rather than by necessity (Laws of New York, § 601(e), 20 NYCRR 132.18). Source: http://www.journalofaccountancy.com/issues/2009/jun/20091371.html Similar text can also be found here: http://www.koscpa.com/newsletter-article/state-tax-consequences-telecommuting/ The NYS tax document governing this situation seems to be TSB-M-06(5)I. I looked at this page from NYS that was mentioned in the answer by @littleadv. That language does at first glance seem to lead to a different answer, but the ruling in the tax memo seems to say that if you're out of state only for your convenience then the services were performed in NYS for NYS tax purpose. From the memo: However, any allowance claimed for days worked outside New York State must be based upon the performance of services which of necessity, as distinguished from convenience, obligate the employee to out-of- state duties in the service of his employer. "Short answer: Yes. For Federal income tax purposes, you are taxed on your total income, adding up positives and negatives. If business A made, say, $100,000 while business B lost $20,000, then your total income is $80,000, and that's what you'll be taxed on. As @littleadv says, of course any business losses you claim must qualify as business losses under IRS rules. And yes, there are special rules about losses that the IRS considers ""passive"". If you have wage income in addition to business income, business losses don't offset wage income for social security and medicare tax purposes. You can't get a refund of the social security tax deducted from your paycheck. I don't know if this is relevant to you, but: If you have businesses in different states, each is taxed by that state. For example I have two tiny side businesses, one in Michigan and one in Ohio. Last year the Michigan business made money while the Ohio business lost money. So my federal income was Michigan minus Ohio. My Ohio income was negative so I owed no Ohio income tax. But I couldn't subtract my Ohio losses from my Michigan income for Michigan income tax purposes. Thus, having, say, $10,000 income in Michigan and $10,000 in Ohio would result in lower taxes than $30,000 income in Michigan and a $10,000 loss in Ohio, even though the total income in both cases is the same. And this would be true even if the tax rates in both states were identical." Unfortunately, the tax system in the U.S. is probably more complicated than it looks to you right now. First, you need to understand that there will be taxes withheld from your paycheck, but the amount that they withhold is simply a guess.  You might pay too much or too little tax during the year.  After the year is over, you'll send in a tax return form that calculates the correct tax amount.  If you have paid too little over the year, you'll have to send in the rest, but if you've paid too much, you'll get a refund.  There are complicated formulas on how much tax the employer withholds from your paycheck, but in general, if you don't have extra income elsewhere that you need to pay tax on, you'll probably be close to breaking even at tax time. When you get your paycheck, the first thing that will be taken off is FICA, also called Social Security, Medicare, or the Payroll tax.  This is a fixed 7.65% that is taken off the gross salary.  It is not refundable and is not affected by any allowances or deductions, and does not come in to play at all on your tax return form. There are optional employee benefits that you might need to pay a portion of if you are going to take advantage of them, such as health insurance or retirement savings.  Some of these deductions are paid with before-tax money, and some are paid with after tax money. The employer will calculate how much money they are supposed to withhold for federal and state taxes (yes, California has an income tax), and the rest is yours. At tax time, the employer will give you a form W-2, which shows you the amount of your gross income after all the before-tax deductions are taken out (which is what you use to calculate your tax).  The form also shows you how much tax you have paid during the year. Form 1040 is the tax return that you use to calculate your correct tax for the year.  You start with the gross income amount from the W-2, and the first thing you do is add in any income that you didn't get a W-2 for (such as interest or investment income) and subtract any deductions that you might have that are not taxable, but were not paid through your paycheck (such as moving expenses, student loan interest, tuition, etc.)  The result is called your adjusted gross income. Next, you take off the deductions not covered in the above section (property tax, home mortgage interest, charitable giving, etc.).  You can either take the standard deduction ($6,300 if you are single), or if you have more deductions in this category than that, you can itemize your deductions and declare the correct amount. After that, you subtract more for exemptions.  You can claim yourself as an exemption unless you are considered a dependent of someone else and they are claiming you as a dependent.  If you claim yourself, you take off another $4,000 from your income. What you are left with is your taxable income for the year.  This is the amount you would use to calculate your tax based on the bracket table you found. California has an income tax, and just like the federal tax, some state taxes will be deducted from your paycheck, and you'll need to fill out a state tax return form after the year is over to calculate the correct state tax and either request a refund or pay the remainder of the tax.  I don't have any experience with the California income tax, but there are details on the rates on this page from the State of California. "It doesn't generally matter, and I'm not sure if it is in fact in use by the IRS other than for general statistics (like ""this year 20% of MFJ returns were with one spouse being a 'homemaker'""). They may be able to try and match the occupation and the general levels and types of income, but for self-employed there's a more precise and reliable field on Schedule C and for employees they don't really need to do this since everything is reported on W2 anyway. So I don't think they even bother or give a lot of value to such a metric. So yes, I'm joining the non-authoritative ""doesn't matter"" crowd." "I have an indirect answer for you. It is not a numeric answer but it is a procedure. The challenge with paying taxes for an employee besides their share of Social security and Medicare is that you have no idea what their state and Federal taxes are.  Are they married, single, head of household? Is this their entire families income, or is it  extra money to make ends meet? What about state taxes?  It looks like you will need a W-4 from them.  As you know the IRS Tax topic 756 has all the info you need. Federal Income Tax Withholding You are not required to withhold federal income tax from wages you pay   to a household employee. However, if your employee asks you to   withhold federal income tax and you agree, you will need a completed   Form W-4 (PDF), Employee's Withholding Allowance Certificate from your   employee. See Publication 15, (Circular E), Employer's Tax Guide,   which has tax withholding tables that are updated each year.  Form W-2, Wage and Tax Statement If you must withhold and pay Social Security and Medicare taxes, or if   you withhold federal income tax, you will need to complete Form W-2   (PDF), Wage and Tax Statement, for each employee. You will also need a   Form W-3 (PDF), Transmittal of Wage and Tax Statement. See ""What Forms   Must You File?"" in Publication 926 (PDF) for information on when and   where to furnish and file these forms. To complete Form W-2 you will   need an employer identification number (EIN) and your employees'   Social Security numbers. If you do not already have an EIN, you can   apply for one using the online EIN application available on IRS.gov.   This service is available Monday through Friday, 7 a.m. to 10 p.m.   Eastern time. You can also apply for an EIN by mailing or faxing a   completed Form SS-4 (PDF), Application for Employer Identification   Number. International applicants may apply by calling 267-941-1099   (not a toll-free number) Monday through Friday, 6 a.m. to 11 p.m.   Eastern time to obtain their EIN. Refer to Topics 752 and 755 for   further information. Don't forget Federal Unemployment Tax. Pub 15 will have tables so you can determine how much you should have been withholding if you had gone that route. It will be easiest to use a spreadsheet to do the calculations so that what you gave them in their checks is their net pay not their gross. The tables are constructed under the assumption you know their gross pay." The W4 specifies withholding for income taxes, FICA taxes are not impacted. The tax withholding is do that you do not need to make estimated tax payments. Failing to make sufficient quarterly estimated tax payments or withholding a sufficient amount could result in you being hit with under payment penalties but nothing more. The under payment penalties will be figured out as part of you income tax return.  What you should have done when you discovered this was use the extra withholding line on the W4 to further increase your withholding. The nice thing about withholding is that you back load it and the IRS does not care.  The company has no liability here. It is your responsibility to update them when your personal circumstances change. You will be fully responsible for the tax bill.  There is no company paid portion of your income tax so they are not impacted. The company only pays an employer share of FICA and that is not impacted by how you fill out the W4. First thing to do is figure out how much you owe the IRS. Then determine if you can pay it or if you need to investigate an installment option. In any case make sure to file your return on time. "In general, following the W-4 instructions should result in withholdings that are fairly close to the amount of taxes that you will owe for the year, particularly if your situation is relatively uncomplicated. Claiming less withholdings than the form suggests can help ensure that you end up saving money in your ""interest-free IRS savings account"" and get a refund at the end of the year, which some people prefer so they don't need to budget separately for a tax payment. I'm guessing that the HR employee either prefers doing so himself or has on occasion received complaints from other employees that they ""didn't take enough out"". Personally, I'd prefer to claim as many withholdings as I can, and be sure to have some money aside in case it turns out that I have to owe a little bit, since it means I get more take-home pay throughout the year. It's good to keep in mind that a W-4 isn't written in stone. If it turns out that too much or too little is being taken out, you can always change it. You can also try playing around with the IRS withholding calculator to try some scenarios." If you make 100K in the U.S., you are most definitely NOT paying 25.7% tax federally. Only money that you made over 37.5K is even charged at 25% AND you didn't even factor in that you get deductions which decrease your effective tax rate. Where are you pulling your numbers? Everyone pays their personal income tax with funds from their employer;  some of it through withholding, and the rest through the balance due at the time of filing. All that is happening here is that the company is calculating  your personal tax return for you, and fiddling retroactively with the gross salary to yield a specific after-tax salary. One problem is that there is a lot of information I put in my return to earn deductions, that I would not care to tell my employer.   The system would also appear to be contrary to public policy.  Governments create tax deductions to give a larger income to those with socially acceptable expenses:  health care, dependents,  etc.  The system you describe would give employees with such deductions a lower gross salary. This is the point of the article. Somehow a company which is so successful has, for tax purposes, such a razor thin margin. So their taxation clearly isn't in keeping with its actual ability to pay, passing along the burden to other businesses and individuals. Are you saying that you did not tell your employer, more specifically, your payroll department, that you got married, via a W4?  The W4 does not say '25%' bracket, but it asks for how many withholding allowances you plan to take. In effect, you are withholding at the single rate, but are married now. When you do your taxes for 2013, you'll see the full effect of what the W4 has on your withholding.  I suggest you use this time to update the W4, and not lend money to Uncle Sam.   Here's the current tax table from FairMark Publishing. 2013 gives a single a combined $10K in standard deduction and exemption, with a couple getting $20K. For a simple return, this is the info you need to figure out what you'll get back, and conversely, how much to pay next year.  e.g. a gross of $50,000 - for single the tax is on $40,000. $5929. For a couple, $30K taxable is a tax of $3608.  On a side note - I strongly recommend Roth accounts when in the 15% bracket and shift to Pre-Tax accounts as you get into the 25% bracket.