As @Nezzer said, why record your invoice in a company with no assets to pay the invoice? You’re just adding to the shareholder’s capital loss. I would have first asked for a retainer to do the bulk of the work for this company. Then I would have told the client that my invoice will go to HIM personally and have him sign an engagement letter to personally guarantee the payment.
I don’t know why you’re so concerned about how this insolvent company accounts for it’s wind-up. The company likely doesn’t need the expense from an accrual and you may be doing yourself a disservice invoicing this insolvent company.
The short answer to your question is that I wouldn’t book it in the company. I would be surprised if your client cares how it is booked. The important person to look after here is the accountant.
Section 80 does not come into play unless the debt was a commercial obligation that entailed an interest component (whether this was between a shareholder loan running balance or intercompany), at which point you would have to adjust your CCA PRIOR to claiming any terminal losses or disposals.
You would have to do 2 returns here, 1 where the fiscal year end has closed, and another on dissolution (where the notice of dissolution has been accepted by the registry, this would be a stub period).
To keep it simple, the debt owed to shareholder should be nulled by a retained earnings deficit, which is the basis for ABIL. You can elect to claim ABIL on the shareholders T1, but note that it is heavily scrutinized by CRA, so you will need to document a bread crumb trail showing the loss wasn’t just the result of a notional balance accrual of any sort.
I wouldn’t recommend booking a fee accrual, as CRA generally treats these as carrying charges and prefers they are brought forward from the previous years billing.