One main client pays my corporation. How do I reduce the CRA risk?

The honest answer: lower the risk, or lower the cost of being wrong

There are only two levers, and a serious plan pulls both at once rather than betting everything on one. The first lever is changing the facts so that, viewed from outside, your corporation looks like a business serving a customer rather than a person serving an employer. The second lever is arranging your compensation so that if CRA looks anyway and wins, the extra tax is small. Consultants tend to obsess over the first lever and ignore the second, which is backwards: the first lever is partly outside your control, because it depends on how your client behaves, while the second lever is entirely inside it.

One more piece of honesty before the mechanics. Concentration alone does not make you a personal services business; plenty of legitimate businesses have one dominant customer. What concentration does is remove your margin for error.

With five clients, a bad contract clause is noise. With one client supplying almost all your revenue, every remaining fact gets weighed, so every remaining fact has to point the right way. That standard is demanding, but it is also concrete, which makes it workable.

This is not a theoretical worry. Personal services business status has been an active CRA review area in recent years, with dedicated projects looking at incorporated contractors in exactly your position, and the profile is easy to spot from filings alone: one corporation, one payer on the invoices, one incorporated employee, full small business deduction claimed. The good news inside that is symmetry. Because the profile is visible on paper, the defence can be built on paper too, which is what the rest of this page is about.

What a personal services business finding actually costs

A personal services business is the most expensive way to earn income through a corporation, which is why the risk deserves respect. If CRA decides your corporation is a PSB for a year, three things happen to that year's income at once:

• The small business deduction disappears. PSB income is carved out of active business income, so the low Ontario combined rate of 12.2% on the first 500,000 dollars never applies. We explain the deduction itself in what is the small business deduction.
• The general rate reduction disappears too, and a 5-point federal addition applies. The result is a combined corporate rate in Ontario of roughly 44.5% on PSB income, higher than the general corporate rate by design, so there is no shelter left in the corporation at all.
• Almost every deduction is denied. A PSB may deduct essentially the salary and benefits it pays its incorporated employee and little else. Home office, vehicle, software, insurance, subcontract help: denied against PSB income, even though the money was genuinely spent.

Stack a 44.5% corporate rate on top of the personal tax you pay when the remaining cash comes out as a dividend, and total tax can land well above what plain employment would have cost, before interest and penalties for the years already filed the wrong way. The dividing line CRA is policing is the one between employment and business income, which is why the definition of active business income is where this whole topic starts.

Two side effects are worth knowing. Reassessments rarely stop at one year: a finding for the year under review invites the same adjustment for every open year, so the bill compounds backward. And your client carries a parallel exposure of its own, because a worker who is in substance an employee raises source deduction and payroll questions on their side, which is precisely why sophisticated clients will often agree to restructure a contract toward genuine independence when it is put to them properly. Their risk is your leverage in the renegotiation.

The test: would you be an employee without the corporation?

The statutory question is blunt: ignoring the corporation, would you reasonably be regarded as an officer or employee of the client you serve? To answer it, CRA and the courts weigh the same factors used in any employee-versus-contractor dispute, and no single factor decides it. The ones that matter:

• Control. Who decides how, when and where the work is done? Set hours, a manager assigning tasks, and required attendance look like employment. Deliverables you schedule yourself look like business.
• Tools and equipment. Whose laptop, licences, and workspace? Working entirely on client-issued equipment inside client systems is an employee pattern.
• Chance of profit, risk of loss. Fixed monthly amounts that never vary carry no business risk. Fixed-price deliverables, unpaid rework, bad-debt exposure and costs you absorb are what real businesses have.
• Integration. Are you on the client's org chart, in their directory, at their staff events, with a title that reads like a role rather than a vendor?
• Ability to subcontract. A genuine right to send a qualified substitute, even if rarely used, is powerful evidence the client bought a result, not you personally.
• Intention and paper. A contract that says independent contractor helps only when conduct matches it. A contract contradicted by daily behaviour can hurt more than no contract.

Two statutory exits exist but rarely apply to a solo consultant: a corporation that employs more than five full-time employees throughout the year is not a PSB, and income from an associated corporation is treated differently. If you are a one-person corporation, assume neither exit is available and plan on the factors.

There is no scorecard where four factors out of six wins. The decision-maker steps back and asks whose business this really is: are you in business on your own account, or slotted into someone else's operation with a corporation in between? That is why the daily reality matters more than any single document.

The useful self-test is brutal and simple. Describe your working week to a stranger without naming your corporation, and ask whether they would call you an employee. If the honest answer stings, that is the gap the next section works on, factor by movable factor.

What you can actually change, factor by factor

Most of the factors are movable, and the useful exercise is comparing your current pattern against the pattern you want to be able to show. This is the table we walk through with incorporated consultants:

On multiple clients specifically: real second and third clients are the strongest medicine, and even modest ones count if they are genuine. A weekend engagement, a retainer with a former colleague's company, paid workshops, a productized service. What matters is being in the market, visibly willing and able to serve others, rather than contractually or practically locked to one payer.

The contract renegotiation is more available than most consultants assume. The ask is not a pay change; it is structure: a master services agreement with statements of work per deliverable instead of an evergreen retainer, a substitution clause, removal of exclusivity, milestone billing, and your own equipment where the client's security rules permit. If you work through a staffing or placement agency, read the chain of contracts, because the agency's paper often describes control and supervision terms you have never seen and would not sign. You are entitled to ask for the terms that describe how you actually intend to work.

Documentation is the quiet half of the defence. Keep the signed contracts and every renewal, invoices that describe deliverables, proof of insurance, records of proposals you sent to other prospects, your marketing, and notes of who supplied what equipment. PSB reviews happen years after the fact; the file you build now is the evidence you will actually have then.

Give the file a cadence rather than a good intention: once a year, alongside the corporate return, refresh it. Save that year's contracts and renewals, export a sample of deliverable-based invoices, note the equipment and licences you paid for, record the proposals and pitches made to other prospects, and date the summary. Ten minutes a year builds the record that, five years from now, answers a review letter with documents instead of memory.

What does not help, and can quietly hurt

Some popular moves add no protection, and a few make things worse. Incorporation itself proves nothing: the PSB rules exist precisely for incorporated workers, so the corporation is the reason the question is being asked, not the answer to it. A token second client invented for optics, one invoice to a relative's company, will not outweigh the daily reality of one payer. A beautifully drafted independent-contractor agreement that your conduct contradicts, badge, manager, set hours, staff meetings, is a trap of your own making, because CRA reads behaviour first and paper second.

Backdating is the move that turns a tax problem into a serious one; the file has to be built in real time. And leaving profits in the corporation to compound at the small business rate, the standard play for a healthy consultancy, is exactly the wrong play when PSB risk is high, because the corporate rate you are betting on is the one a reassessment takes away. Deferral strategy for owner-managed corporations is covered in corporate tax planning for owner-managed businesses; the point here is that PSB exposure changes which of those strategies are safe for you.

Paying yourself in dividends while the risk is high deserves its own warning, because it is the worst of both worlds. Dividends are not deductible, so under a PSB finding the corporation pays roughly 44.5% on the income and you still pay personal dividend tax on the way out, with none of the salary deduction that would have hollowed the corporate bill. Dividends also skip RRSP room and CPP, the two things that soften the landing if the engagement is ever recharacterized. High PSB risk and a dividends-only pay policy is the combination we move clients off first.

The salary fallback, the facts that swing it, and how we handle it

The compensation design that caps the damage is simple: a PSB may still deduct the salary and taxable benefits it pays you, so paying essentially all of the corporation's profit out to yourself as salary each year leaves little or no corporate income for the punitive rate to bite. You lose the deferral advantage of a corporation, but a reassessment then costs comparatively little, because the corporation had nothing left to tax. Consultants with high PSB risk who bonus down to nil each year are buying insurance with the deferral they give up, and for many of them it is the right trade until the facts improve.

The defence is not all-or-nothing, either. A consultant whose facts are mixed might retain modestly and salary the rest, then loosen the policy as second clients land and the contract improves, or tighten it when a renewal quietly reintroduces exclusivity. The salary level becomes a dial you set to your current risk score, reviewed annually, which is a far better position than a fixed habit set years ago under different facts.

Whether to run that defence, and how hard to push the factor work, turns on a short list of facts:

• How employee-like the engagement really is: hours, manager, badge, exclusivity, or a genuine deliverables arrangement
• Whether a second client is realistic in your field within the next year, or the engagement contract forbids it
• How much profit you want to leave in the corporation: the more you defer, the more a reassessment costs
• The contract's terms and who will renegotiate them: some clients will happily move to deliverables-based terms, some never will
• Your history: years already filed with full deductions and retained earnings raise the stakes of doing nothing

Our work as a corporate tax planning CPA firm in Ontario is to score those facts honestly, fix the contract and conduct where they can be fixed, build the documentation file, and set a salary policy that matches your actual risk level, then revisit all of it each year as the engagement evolves. The review is blunt by design, because a consultant who hears a comfortable answer now meets an uncomfortable one at reassessment, with interest. That runs inside Tax Planning & Advisory, with the T2 filed to match through Corporate Tax. If most of your income comes from one client and none of this has ever been assessed, a free 15-minute discovery call is the cheapest risk review you will ever do.