I may earn a lot of cash soon through self-employment on a lucrative project.  How to handle the tax?
Seek professional advice as duffbeer703 has suggested already.  Very important! Consider incorporating.  If your income will fluctuate year to year, you can keep profit in the corporation, taxed in its hands at the Canadian small business rate, since such corporate income below $500,000 would likely qualify for the small business deduction. You could pay  retained earnings to yourself as dividends over more than one year in order to lessen the personal tax burden. If you don't incorporate, all your profits in the year they are earned are taxed at personal income tax rates, and with our progressive income tax system, taking the tax hit all in one year can be expensive.  However, if this project is a one-off and you're not likely to continue working like this, you might not want the overhead of a corporation.  Taxes aside, there are also legal issues to consider vis-a-vis incorporating, or not. A professional can help you make this decision.   Yes, you can claim deductions for reasonable business expenses, whether or not you are incorporated. No, you can't do free work on the side and claim it as donations.  It's nice to volunteer, but you wouldn't get a charitable tax credit for your time, only for money or goods donated. Consider opening an RRSP so you can start saving for retirement and get a tax deduction for any contributions you make.  This is but one strategy to reduce your tax.  There are others.  For instance, if you are a student, you perhaps have some unused tuition credits that you could claim in your first year with higher income. Oh, and seek professional advice!   ;-) I'm not familiar with Canadian taxes, but had your question been written about the United States, I'd advise you to at least consult for a couple of hours with an accountant. Taxes are complex, and the cost of making a mistake generally exceeds the cost of getting professional advice.
It will depend on how much you expect to earn this way, and whether you expect the company to become profitable soon. Has the company just not made a profit yet, or has it actually made a significant loss that your invoices would just be offsetting? If you're earning over £10,000 per year then invoicing through the company is preferable. Above that level, you'd be taking money from the company as dividends after paying 20% corporation tax with no other tax to pay on your personal tax return. As a sole trader you'd be paying 20% income tax and 9% NI. (Note however that the company can only pay dividends from profits, which is a problem if there are significant losses to offset.) Below £10,000, there's little difference. Through the company, you can take a salary of £7956 per year without paying any income tax or NI. With the new £2000 discount on employers' NI you could then take salary up to £10,000 and just pay 12% employee's NI. As a sole trader, you pay 9% Class 4 NI over £7956 and a fixed £143 per year for Class 2 NI. Paying 9% rather than 12% saves you £60, but then you add the £143. In practice the company would work out more expensive at this level because you'll probably want to pay an accountant to deal with the payroll for you. Having the company repay your £2000 from the invoices doesn't really save any tax if the company will become profitable in the future. You don't pay any tax now since the money you receive isn't income, and the company doesn't pay any tax if the extra £2000 of revenue doesn't put it back in profit. However, if the company is profitable next year then it will have an extra £2000 of profit that would otherwise have been offset against this year's loss, and you do end up paying 20% corporation tax on the £2000. You could still have the company repay the loan in order to delay the tax liability, but it's not really tax free money. Loaning additional money to the company has no tax benefit, you just give the company £1000 and get your original £1000 back later. You pay no tax and neither does the company, but it was your money in the first place. 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. "You can (and definitely should) withdraw any part of the contribution that will put you over the contribution limit.  You can (and should if you need to) withdraw to repay any medical payments you made from outside the account.  You can (but should avoid at all costs) withdraw (distribute) from the HSA for non-medical reasons. Here's the IRS publication which covers this:  https://www.irs.gov/publications/p969 Here's the bit about distributions that covers what you're trying to do: You can receive tax-free distributions from your HSA to pay or be reimbursed for qualified medical expenses you incur after you establish the HSA. If you receive distributions for other reasons, the amount you withdraw will be subject to income tax and may be subject to an additional 20% tax. You don’t have to make distributions from your HSA each year.  It is better to pay from your checking and reimburse than to over-fund the HSA.  Best route forward is to reduce your contributions for the rest of the year, especially if continuing them will cause excess contributions.  Another nasty gotcha: Excess contributions.     You will have excess contributions if the contributions to your HSA for the year are greater than the limits discussed earlier. Excess contributions aren’t deductible. Excess contributions made by your employer are included in your gross income. If the excess contribution isn’t included in box 1 of Form W-2, you must report the excess as ""Other income"" on your tax return. Generally, you must pay a 6% excise tax on excess contributions. See Form 5329, Additional Taxes on Qualified Plans (Including IRAs) and Other Tax-Favored Accounts, to figure the excise tax. The excise tax applies to each tax year the excess contribution remains in the account.  You may withdraw some or all of the excess contributions and avoid paying the excise tax on the amount withdrawn if you meet the following conditions.  •You withdraw the excess contributions by the due date, including extensions, of your tax return for the year the contributions were made. •You withdraw any income earned on the withdrawn contributions and include the earnings in ""Other income"" on your tax return for the year you withdraw the contributions and earnings. If you will not be over your maximum contribution, let the contribution ride.  Make sure your HSA balance is divided between cash, stock fund, bond fund.  Much like your 401k.  Because the part that you don't spend on medical expenses this year can be spent in future years' medical expenses, and if you have anything left when you retire you can spend it on whatever you want.  And the funds, including growth, are not taxed until you distribute them. Bottom line:  if the funds will not cause excess contribution, leave them in.  Otherwise, take them out as soon as possible." Your freelance income will not qualify you for the work-from-home deductions, for that you would need a T2200 form signed by your employer. But, you are allowed to be self employed as a sole-proprietorship while still being an employee of another company. If you take that route, you'll be able to write-off even more expenses than those you linked to. Things like a portion of your internet bill can be claimed, for example. But note that these deductions would only apply to offset the self-employment income, so if you're not earning very much from the freelance work, it might not be worth all the hassle. Filing taxes when self-employed is definitely more complicated, and many people will get professional tax preparation help - at least for the first time. Use a limited company. Use the HMRC website for help on limited companies and get a good accountant for doing your taxes. Mixing your website income and personal income  may make you pay a higher tax rate. You can take out expenses from the limited company, which are tax deductible. But if you group it in personal income it wouldn't be tax deductible. In a personal capacity you are 100% liable if your business goes bust and you owe debt. But for a limited company you are only liable for what you own i.e %age of shares. You can take on an investor if your business booms and it is easier if you do it through a limited company rather than through a personal endeavour. "One way to do these sorts of calculations is to use the spreadsheet version of IRS form 1040 available here.  This is provided by a private individual and is not an official IRS tool, but in practice it is usually accurate enough for these purposes.  You may have to spend some time figuring out where to enter the info.  However, if you enter your self-employment income on Schedule C, this spreadsheet will calculate the self-employment tax as well as the income tax.  An advantage is that it is the full 1040, so you can also select the standard deduction and the number of exemptions you are entitled to, enter ordinary W-2 income, even capital gains, etc. Of course you can also make use of other tax software to do this, but in my experience the ""Excel 1040"" is more convenient, as most websites and tax-prep software tend to be structured in a linear fashion and are more cumbersome to update in an ad-hoc way for purposes like tax estimation.  You can do whatever works for you, but I would recommend taking a look at the Excel 1040.  It is a surprisingly useful tool." Wanna make sure every company pays at least some taxes? Install a 'tax floor'. Basically, no matter how many losses you claim, no matter how much you offshore, no matter how many loopholes you find, you can not drop below a certain number. Let's say 15%. That is it, you have to pay at least 15%.   As this takes effect, and only after revenues stream in for a few years to help balance things out, you can even slightly adjust the high rate down a tad to help the big companies that don't use the loopholes.  Please spread this idea around. If you're not insolvent, doing something like this is both a moral and legal hazard: When you are insolvent, the tax and moral hazard issues can be a non-issue. Setting up a scenario that makes you appear to be insolvent is where the fraud comes in. If you decide to go down this road, spend a few thousand dollars on competent legal advice.