Sorting Out Input Tax Credits On A Mixed-Use Building

The situation

By the time Kostas came to us, he had already spent two weekends going through online forums trying to work out why the Canada Revenue Agency had flagged his HST return, and none of what he found there matched the letter now sitting on his kitchen table. He had arrived in Canada a little over a year earlier and, drawing on savings from selling a property overseas, bought a small building in Perth with a retail unit on the ground floor and two apartments above it. He worked as a bookkeeper, so numbers were not unfamiliar to him, but Canadian tax rules were, and this was the first return he had ever filed here.

He had spent a fair amount on renovations before renting the units out: new flooring, updated plumbing, and repairs to the storefront so it could be leased as a hairdressing salon. When it came time to file, he searched online for how to claim back the HST he had paid on that work and found several posts describing input tax credits as something a landlord could simply claim on renovation costs. He applied that advice to the whole renovation bill and claimed the full amount as a credit on his return. It seemed straightforward at the time, and the credit reduced what he owed CRA by an amount that made a real difference to his finances that year.

Months later, a CRA reviewer named Latif wrote to him asking for documentation supporting the credit and, after receiving Kostas's invoices, proposed to disallow most of it. Kostas tried responding on his own first, resending the same invoices with a cover letter explaining the renovation work, but the position did not change, because the problem was not whether the expenses were real, it was how much of the building they related to. His tenant Farid, who ran the salon downstairs and had become a friend, was the one who eventually suggested he stop trying to sort it out alone and get proper advice before the numbers got any bigger. Farid had gone through his own HST registration when he set up the salon lease and remembered how confusing the commercial rules had been even for a straightforward retail tenancy, which made him suspect that Kostas's situation, spanning both a shop and two apartments, was more complicated than a forum post could really cover.

What the review found

When we went through the building's HST history, the core issue was clear: input tax credits are available only for expenses tied to a commercial activity. Long-term residential rent is an exempt supply, so HST on costs connected to it generally cannot be recovered, which was the case for Kostas's two apartments. Short-term accommodation is treated differently, since renting a residential unit for stays of under a month at typical nightly rates counts as a taxable supply rather than an exempt one, but that was not Kostas's situation here. A building with retail space downstairs and apartments above is a mixed-use property, meaning some of it supports commercial activity that generates HST-taxable rent, and some of it supports residential tenancies that do not. The renovation invoices Kostas had claimed in full covered both parts of the building at once, since the plumbing and structural work in particular served the whole property rather than just the salon.

The online guidance Kostas had followed was not entirely wrong, it was just written for a different situation. A landlord who is registered for HST and rents purely commercial space can generally claim the HST on renovation costs in full, because commercial rent is a taxable supply, provided the registration was in place at the time and the invoices hold the right supporting details. What the posts he found had not addressed was what happens when a single building serves both commercial and residential tenants, where the credit has to be apportioned to reflect only the portion of the expense connected to the commercial use. Without that apportionment, Kostas had effectively claimed credit for HST connected to the apartments upstairs as well as the salon below, and the apartments generated no taxable rent to justify it.

Working out a fair apportionment required more than a guess. We reviewed the floor plans and the renovation invoices line by line to separate work that was genuinely commercial, such as the storefront repairs, from work that served the whole building, such as the plumbing and roof repairs, and from work that was purely residential, such as flooring inside the apartments. For the shared expenses, floor area became the fairest basis for splitting the cost between the roughly one-third of the building used commercially and the two-thirds used as residential apartments. That recalculation produced a credit figure well below what Kostas had originally claimed, but well above the near-total denial Latif had proposed, because several invoices were, in fact, entirely commercial in nature and had been swept into the disallowance along with everything else. It also mattered that the salon lease itself was properly structured as a taxable commercial tenancy, since that was what made the retail portion of the building eligible for credits in the first place. If Kostas had instead rented the ground floor unit out on a residential basis, none of the renovation HST connected to it would have qualified either, mixed-use or not, which is a distinction the online guidance he had relied on never addressed at all.

What we did

1. Gathered every renovation invoice and matched each one to a specific area of the building, because the apportionment CRA required could not be done accurately without knowing which costs related to the salon, which related to the apartments, and which served the building as a whole, and Kostas's original filing had not made that distinction at all. This meant going back to the contractor for a breakdown that some of the original invoices had bundled into a single line.
2. Measured the actual floor area of the commercial and residential portions from the building's own plans, since apportioning shared expenses fairly required a defensible basis rather than an estimate, and floor area is a method CRA reviewers commonly accept for this kind of mixed-use split when it is properly documented against the building's actual layout. We had the measurements confirmed against the municipal property record rather than relying on the plans alone, since a discrepancy between the two would have undermined the whole apportionment.
3. Recalculated the input tax credit claim from scratch using the corrected apportionment, separating expenses that were fully commercial, fully residential, and shared, so that the revised number reflected only the HST genuinely connected to the taxable retail use of the building rather than the whole renovation bill. Rebuilding the claim this way, invoice by invoice, gave us a figure we could defend line item by line item if the reviewer challenged any single entry, rather than one blended total.
4. Prepared a written response to Latif's proposal that explained the apportionment methodology and attached the supporting floor area and invoice breakdown, because the earlier response Kostas had sent on his own repeated the invoices without addressing why the full amount had been claimed in the first place, which is likely why it had not moved the reviewer's position. Showing the reasoning behind the split, not just a revised number, gave the reviewer something concrete to evaluate against CRA's own apportionment guidance.
5. Requested a meeting with the reviewer to walk through the recalculation directly, since a mixed-use apportionment dispute often turns on whether the reviewer accepts the split proposed, and a conversation let us address Latif's specific concerns about the shared expenses in real time rather than through several more rounds of letters. That direct exchange also let us learn which specific invoices Latif still doubted, so the next submission could target exactly those items instead of resubmitting the whole file again.
6. Negotiated the treatment of the disputed shared costs, ultimately agreeing on a split close to the floor area calculation for most items, while accepting a more conservative allocation for a small number of invoices where the commercial connection was harder to document clearly, which kept the file from stalling over a handful of ambiguous line items, since holding out for the full floor area split on every last invoice would likely have dragged the review out for months without changing the final number by much.
7. Worked out a payment arrangement for the balance still owing, since even after the recalculation Kostas owed a real amount back, and spreading that over manageable installments meant he could pay it down without disrupting the rest of the building's finances. We sized the installments against his actual rental income from both the salon and the apartments, rather than an arbitrary schedule, so the arrangement was one he could realistically sustain.
8. Confirmed the corrected filing and payment arrangement in writing, so Kostas had a clear record of what had been allowed, what had been denied, and what he still owed, closing the file with a defined number instead of an open dispute that could resurface later. This written confirmation also set out the apportionment method itself, so any future renovation claim on the same building would start from an agreed methodology rather than a fresh dispute.

The outcome

The final result split the difference between what Kostas had originally claimed and what Latif had first proposed to allow. A meaningful portion of the input tax credit was restored once the fully commercial expenses, like the storefront repairs, were separated out and no longer swept into the general disallowance. But Kostas also had to accept that the residential share of the shared renovation costs, the roughly two-thirds tied to the apartments, was never eligible for the credit in the first place, and that portion of what he had originally claimed stayed reversed, along with interest for the period the credit had been sitting on his account.

He ended up owing CRA an amount in the low tens of thousands, a real cost, but well below what the initial proposal would have left him with if he had not challenged the shared-expense allocation at all. The building continued operating as it had, with Farid's salon downstairs and the two apartments rented above, and Kostas set up his bookkeeping going forward to track commercial and residential expenses separately from the start rather than reconciling them after the fact.

Kostas has said since that the hardest part was not the dispute itself but recognizing that the advice he had trusted online had been written for someone in a different situation than his. Once the apportionment was properly worked out, the outcome was not the full credit he had first claimed, and it was not the near-total denial CRA had first proposed either. It was a number both sides could support with the actual math, which is closer to what mixed-use HST claims are supposed to look like from the start. Latif's review closed on the strength of that shared calculation, and Kostas came away with a bookkeeping habit, tracking commercial and residential costs separately as they are incurred, that should keep the same mistake from recurring the next time he renovates any part of the building.

What you can learn from this