Assignment Sale HST: How It's Calculated and Who Pays

HST is one of the most commonly misunderstood costs in a condo assignment sale — and getting it wrong can turn a profitable assignment into a much thinner one. Here's how it actually works.

Two Separate HST Questions in Every Assignment

An assignment sale actually has two distinct HST considerations, and conflating them is where most confusion starts:

1. HST on the original purchase price (paid to the builder at final closing). This is the standard HST embedded in any new construction purchase, typically already factored into the builder's price and offset in part by the standard new-housing rebate most buyers are familiar with. This obligation transfers with the assignment — as the assignee, you generally step into the original buyer's position for this portion at final closing.

2. HST on the assignor's profit. This is the part that catches people off guard. If the original buyer (the assignor) sells their assignment for more than they originally paid in deposits, the profit portion of that assignment sale is generally subject to HST, treated by the Canada Revenue Agency as a taxable supply.

Who Actually Pays It

In most GTA assignment transactions, the assignor's profit is subject to HST, and the assignor is responsible for remitting it — but the contract terms determine whether that HST is already baked into the assignor's asking price or added on top for the assignee to pay. This is exactly the kind of detail that needs to be explicitly addressed in the Assignment Agreement of Purchase and Sale, not assumed by either party.

Two common structures show up in GTA assignment contracts:

• HST included in the assignment price: The assignor's profit figure already accounts for the HST they'll owe, so the assignee's total cost is simpler.

• HST added on top: The assignee pays the assignor's profit plus HST on that profit as a separate line item at the assignment closing.

Neither structure is automatically "correct" — it's negotiated between the parties, which is exactly why the contract language matters more here than in almost any other part of an assignment deal.

Why This Trips Up First-Time Assignment Sellers

Many original buyers list their assignment based purely on their target profit number, without factoring in that the CRA will treat a meaningful chunk of that profit as taxable. An assignor expecting to net $100,000 who hasn't accounted for HST on that gain can end up with significantly less than expected once the tax obligation is settled.

Why This Matters for Buyers Too

As the assignee, even if you're not the one remitting HST on the assignor's profit, you need absolute clarity on whether it's included in your total cost or payable on top — this single line item can shift your true purchase price by tens of thousands of dollars depending on how the contract is structured.

The New Housing Rebate Complication

The original buyer's eligibility for the standard new-housing HST rebate is generally based on the original purchaser's intent at the time they signed with the builder — not the assignee's intent. If the original buyer intended the unit as an investment (not their primary residence) and claimed or was ineligible for a specific rebate structure, that history can carry forward and affect the final numbers at closing in ways that aren't always obvious from the assignment contract alone.

What to Do Before You Sign Anything

• Have a real estate lawyer experienced specifically in assignment transactions review the HST clauses before you sign either side of the deal.

• Get written confirmation of whether HST is included or additional before you agree on a final assignment price.

• Ask your assignor (if you're buying) what rebate structure applied to their original purchase — this history follows the unit.

The Bottom Line

HST on an assignment sale is genuinely one of the more technical pieces of the transaction, and it's exactly the kind of detail that gets glossed over in a handshake negotiation between an eager buyer and seller. Get it in writing, get it reviewed, and don't assume it works the same way it did on the last assignment you heard about from a friend.

Buying or selling an assignment in the GTA and want the HST structure handled correctly from the start? Contact AssignmentPlus — our team works through this exact detail on every transaction.

This article provides general information and is not tax advice. Consult a real estate lawyer and accountant for guidance specific to your transaction.