Tax Write-offs and knowing how much I need to spend before the end of the year
"(I'm assuming USA tax code as this is untagged) As the comments above suggest there is no ""right"" answer or easy formula.  The main issue is that you likely got into business to make money and if you make money consistently you will pay taxes.  Reinvesting generally should be a business decision where the main concern is revenue growth and taxes are an important but secondary concern. Taxes can be complicated, but for a small LLC shouldn't be that bad.  I highly recommend that you take some time closely analyze your business and personal taxes for the previous year.  Once you understand the problem better, you can optimize around it.  If it is a big concern, some companies buy software so they can estimate their taxes periodically through the year and make better decisions."
I've given up on trying to understand how the allowances correspond to my number of dependents.   What I do instead to achieve the same end goal of having the right amount of money withheld is using a paycheck calculator. If I get paid 24 times a year (twice a month) and I figure I'm going to owe about $6,000 of taxes, then every paycheck needs to have $250 of federal tax withheld from it to make sure I am covered. Go to the paycheck calculator and play with the allowance numbers until you get $250 as the federal tax withheld and then submit a new W4 to your employer. This is the only reliable way I've found to figure this out on my own.  Because my calculations are done in dollars instead of exemptions, etc. and my taxes do not wildly fluctuate year-to-year this works well for me. 1040ES uses the smaller number because that's what triggers the penalties.  (That is, you are penalized if what you prepay is less than your total 2013 liability and less than 90% of your 2014 liability.)  However, estimated taxes are just estimates.  If you pay too little, you could face a penalty, but there's no penalty for paying too much -- you'll just get a refund as usual. It seems that your concern stems from the fact that this is the first year you're in this tax situation and so you're unsure if your estimates are accurate.  In your comment to Pete Belford's answer, you also indicated you aren't worried about being unable to pay, but only about accidentally underpaying. In this case, you could just err on the side of caution and pay more than 1040ES says you owe.  (You don't actually file the 1040ES, the calculations are just for your own use.)  For instance, you could prepay based on the higher of your two estimates, if you can afford it; or, if you can't afford that much, hedge the estimate payments up a bit to an amount you can afford that is closer to the higher estimate.  At the end of the year if you paid too much you can get a refund as usual.  After this year, you will presumably have a better sense of your income and your tax liability, and can make more accurate estimates for next year. $3,679,163.80  I made these assumptions that you did not state:  Then using Excel, we find that with a starting point of $3,679,163.80, we can achieve your goal. The formula for Yearly Budget is =G$1*((1.035)^(A3-2012)) and the formula for Money left at year end is =(D4/1.05)+C4  For 2067, enter $0 leftover, and for 2066, enter $397,988.47 leftover. G$1 is $60,000 G$2 is 0.05 "There are way too many details missing to be able to give you an accurate answer, and it would be too localized in terms of time & location anyway -- the rules change every year, and your local taxes make the answer useless to other people. Instead, here's how to figure out the answer for yourself. Use a tax estimate calculator to get a ballpark figure. (And keep in mind that these only provide estimates, because there are still a lot of variables that are only considered when you're actually filling out your real tax return.) There are a number of calculators if you search for something like ""tax estimator calculator"", some are more sophisticated than others. (Fair warning: I used several of these and they told me a range of $2k - $25k worth of taxes owed for a situation like yours.) Here's an estimator from TurboTax -- it's handy because it lets you enter business income. When I plug in $140K ($70 * 40 hours * 50 weeks) for business income in 2010, married filing jointly, no spouse income, and 4 dependents, I get $30K owed in federal taxes. (That doesn't include local taxes, any itemized deductions you might be eligible for, IRA deductions, etc. You may also be able to claim some expenses as business deductions that will reduce your taxable business income.) So you'd net $110K after taxes, or about $55/hour ($110k / 50 / 40). Of course, you could get an answer from the calculator, and Congress could change the rules midway through the year -- you might come out better or worse, depending on the nature of the rule changes... that's why I stress that it's an estimate. If you take the job, don't forget to make estimated tax payments! Edit: (some additional info) If you plan on doing this on an ongoing basis (i.e. you are going into business as a contractor for this line of work), there are some tax shelters that you can take advantage of. Most of these won't be worth doing if you are only going to be doing contract work for a short period of time (1-2 years). These may or may not all be applicable to you. And do your research into these areas before diving in, I'm just scratching the surface in the notes below." "First, point: The CRA wants you to start a business with a ""Reasonable expectation of profit"". They typically expect to see a profit within 5 years, so you may be inviting unwanted questions from future auditors by using a breakeven strategy. Second point: If the goal is to pay as little tax as possible, you may want to consider having the corporation pay you as little as possible. Corporate income taxes are much lower than personal income taxes, according to these two CRA links: How it works is that your company pays you little as an outright salary and offers you perks like a leased company car, expense account for lunch and entertainment, a mobile phone, computer, etc. The company owns all of this stuff and lets you use it as part of the job. The company pays for all this stuff with corporate pre-tax dollars as opposed to you paying for it with personal after-tax dollars. There are specifics on meals & entertainment which modify this slightly (you can claim 50%) but you get the idea. The actual rate difference will depend on your province of residence and your corporate income level.  There is also a requirement for ""Reasonable Expenses"", such that the expenses have to be in line with what you are doing. If you need to travel to a conference each year, that would be a reasonable expense. Adding your family and making it a vacation for everyone would not. You can claim such expenses as a sole proprietor or a corporation. The sole-proprietorship option puts any after-expense profits into your pocket as taxable income, where the corporate structure allows the corporation to hold funds and limit the amount paid out to you.  I've seen this strategy successfully done first-hand, but have not done it myself. I am not a lawyer or accountant, consult these professionals about this tax strategy before taking any action." "I see you have posted other questions regarding household budgets.  This is a huge first step.  Once you see what is coming in, then list everything that goes out regularly...and then try to break down what is leftover into spending, household maintenance, gifts, haircuts, whatever...it becomes very obvious if you have x to spend and you spend 3x. I budget a certain amount of discretionary money for both my husband and myself to spend each month.  All of our basic expenses are covered under other categories, but I found out long ago that we each need some money to blow on Starbucks, DVD's, books, etc without having to defend or explain it.  If we spend too much, it digs into the next month's amount, or if we are careful, we get to carry it over. I can impulse shop guilt free because it's budgeted in. Long story short, if you set up a budget and have an amount budgeted for most reasonable expenses, and see what is left over...it becomes harder to ""unwittingly"" overspend.  When you are paying attention to your money, and start looking carefully at how you are spending it, you'll notice." I know this is an old question, but for others who may be wondering the same thing, Kualto.com does precisely this. You enter your expected expenses/income and it shows you the beginning and ending balance of each week. You can navigate ahead as much as you want to see how expenses today will affect your account balance in the future. Interesting. When you say DIY you mean pencil and paper. For most of us the choice came down to using a professional vs using the software.  Your second bullet really hits the point. The tax return is a giant spreadsheet with multiple cells depending on each other. Short of building my own spreadsheet to perform the task, I found the software, at $30-$50, to be the happy medium between the full DIY and the Pro at $400+.  With a single W2, and no other items, the form is likely just a 1040-EZ, and there shouldn't be any recalculating so long as you have the data you need. Pencil/paper is fine.  There's no exact time to say go with the software, except, perhaps, when you realize there are enough fields to fill out where the recalculating might be cumbersome, or the need to see the exact tax bracket has value for you.  You are clearly in the category that can fill out the one form. At some point, you might have investment income (Schedule D) enough mortgage interest to itemize deductions (Schedule A) etc. You'll know when it's time to go the software route.  Keep in mind, there are free online choices from each of the tax software providers. Good for simple returns up to a certain level. Thanks to Phil for noting this in comments.  I'll offer an anecdote exemplifying the distinction between using the software as a tool vs having a high knowledge of taxes. I wrote an article The Phantom Tax Zone, in which I explained how the process of taxing Social Security benefits at a certain level created what I called a Phantom Tax Rate. I knew that $1000 more in income could cause $850 of the benefit to be taxed as well, but with a number of factors to consider, I wanted to create a chart to show the tax at each incremental $1000 of income added. Using the software, I simply added $1000, noted the tax due, and repeated. Doing this by hand would have taken a day, not 30 minutes.  For you, the anecdote may have no value, Social Security is too far off. For others, who in March are doing their return, the process may hold value. Many people are deciding whether to make their IRA deposit be pre-tax or the Post tax Roth IRA. The software can help them quickly see the effect of +/- $1000 in income and choose the mix that's ideal for them. Whether you're self-employed or not, knowing exactly how much tax you will pay is not always an easy task.  Various actions you can take (e.g., charitable donations, IRA contributions, selling stocks) may increase or reduce your tax liability. One tool I've found useful for estimating federal taxes is the Excel 1040 spreadsheet.  This is a spreadsheet version of the income tax return form.  It is not official and is not created by the IRS, but is maintained as a labor of love by a private individual.  In practice, however, it is pretty much an accurate implementation of the tax calculation algorithms encoded in the tax forms and instructions. The nice thing about it is that it's a spreadsheet.  You can plug numbers into various slots in the spreadsheet and see how they affect your federal tax liability.  (You may also owe state taxes depending on what state you live in.)  Of course, the estimates you get by doing this are only (at most) as accurate as your estimates of the various numbers you plug in.  Still, I think it's a free and useful way to get a ballpark estimate of your tax liability based on numbers that you can more easily estimate (e.g., how much money you expect to earn). "It's likely you don't have to make estimated tax payments if this is your first year of contracting (extra income), and your existing salary is already having taxes withheld. If you look at the 1040-ES: General Rule In most cases, you must pay estimated tax for 2014 if both  of the   following apply. This is easier to understand if you look at the worksheet.  Look at line 14b/14c and the associated instructions.  14b is your required annual payment based on last year's tax.  14c is the lesser of that number and 14a, so 14b is your ""worst case"".  14c is the amount of tax you need to prepay (withholding counts as prepayment). I'm going to apply this to your situation based on my understanding, because it's not easy to parse:" "Gail Vaz-Oxlade from the television show Til Debt Do Us Part has a great interactive budget worksheet that helps you set up a ""jar"" or envelope system for each month based on your income and fixed expenses.  We have used this successfully in the past.  What we found most useful was, as others have said, writing everything down, keeping receipts, and thus being accountable and aware of our spending." One thing that kept me from doing a budget for years is how complex some people make it.  For example you list your gross pay, then deduct the taxes, 401K, FSA, etc...  Why?  Those are pretty consistent. For me, the way this is budgeted is I list my net pay, and go from there.  If you were perfect in predicting your FSA, you would have no medical expenses on your budget!  Simple, easy budget! Now this year, you will probably have to pay out of pocket for some expenses.  Can you predict how much?  Can your disposable income absorb the overages?  If not you will need to start a sinking fund.  That is put a sufficient amount of money into a savings account each month to cover the shortage.    Keep in mind you can go over a bit on your FSA contributions.  If you find yourself near the end of the plan year with extra money, you can also claim mileage reimbursement for your medical appointments.  Since your FSA has a history of those, it is easy to calculate your mileage from your home to the DR's office and submit a claim. "So after a great deal of clarification, it appears that your question is how to adjust your withholding such that you'll have neither a refund, or a balance due, when you do your 2016 taxes next year.  First, a little terminology. The more you have withheld, the more money will be taken out of your check to cover your estimated tax liability. Confusingly, the more allowances you select on your W-4, the less money you will have withheld (more allowances means more dependents/deductions/other reasons why you will owe less tax). When you go to file your 2015 tax return next year, you'll figure out exactly how much you owe. If you had too little tax withheld, you'll have to pay the difference. If you had too much tax withheld, you'll get a refund back.  Given your situation, simply following the instructions on the W-4 should work pretty well. If you want to be more precise, you can use the IRS Withholding Calculator to figure the number of allowances and submit a new W-4 to your employer.  It's a little hard to tell whether ""paying this much/year in taxes seem steep?"" because you've lumped all the taxes together in one big bucket. Does the $543.61 in taxes per paycheck include Social Security (OASDI) and Medicare taxes? Whatever you do, it's not going to be an exact science. Come tax time, you'll figure out exactly what you owe and either pay the balance or get a refund back. As long as you're relatively close, that's fine. You can always adjust your withholding again next year after you've done your taxes." I would take each of these items and any others and consider how you would count it as an expense in the other direction. If you have an account for parking expenses or general transportation funds, credit that account for a refund on your parking. If you have an account for expenses on technology purchases, you would credit that account if you sell a piece of equipment as you replace it with an upgrade. If you lost money (perhaps in a jacket) how would you account for the cash that is lost? Whatever account would would subtract from put a credit for cash found. I think you might benefit from adopting a zero-sum budget, in which you plan where each dollar will be spent ahead of time, rather than simply track spending or worry about the next expense. Here's a pretty good article on the subject: How and Why to Use a Zero-Sum Budget. This is the philosophy behind a popular budgeting tool You Need a Budget, I am not advocating the tool, but I am a fan of the idea that a budget is less about tracking spending and more about planning spending. That said, to answer your specific question, one method for tracking your min-needed for upcoming expenses would be to record the date, expense, amount due, and amount paid as shown here:  Then the formula to calculate the min-needed (entered in E1 and copied down) would be: As you populate amounts paid, the MinNeeded is adjusted for all subsequent rows. You could get fancier and only populate the MinNeeded field on dates where an expense is due using IF().