diff --git a/docs/superpowers/specs/2026-05-12-nexa-coa-design.md b/docs/superpowers/specs/2026-05-12-nexa-coa-design.md
index 843a0909..4e9b9e42 100644
--- a/docs/superpowers/specs/2026-05-12-nexa-coa-design.md
+++ b/docs/superpowers/specs/2026-05-12-nexa-coa-design.md
@@ -17,6 +17,13 @@ Nexa Systems Inc is a Canadian CCPC providing IT services: custom software devel
 - **Historical Odoo data is NOT authoritative** — accountant has filed externally on Excel-based records. Past will be reconciled later.
 - All prior years filed with CRA. Fiscal year-end Dec 31.
 
+**CRA registration & filing cadence**:
+- **Business Number / HST account**: `741224877` (currently stored as 9-digit BN root only on company record; needs to be updated to full 15-char format `741224877 RT0001` for Odoo's Canadian tax reports to validate cleanly).
+- **GST/HST filing**: annual. Return due **3 months after fiscal year-end** (March 31).
+- **T2 corporate income tax filing**: annual. Return due **6 months after fiscal year-end** (June 30). Balance owing due 3 months after year-end (March 31) for CCPCs eligible for SBD; 2 months otherwise.
+- **HST instalments**: annual filers must remit quarterly instalments if their net tax for the prior year was ≥ $3,000. Track via account 118200 GST/HST Instalments Paid.
+- **T2 instalments**: monthly or quarterly instalments required if Part I tax owing in prior year ≥ $3,000.
+
 **Goals**:
 1. **CRA compliance** — clean tax handling, T2 Schedule 125 alignment, audit-ready
 2. **Tax savings** — SR&ED claim infrastructure from day 1, zero-rated export handling, CCA structure
@@ -510,7 +517,7 @@ Already installed. Use for SaaS/Hosting/Support contracts: recurring invoices, S
 | Zero-rated exports | Fiscal position for US/international | $5–15k recovered HST on inputs | Per-company |
 | Small Business Deduction (SBD) | Federal 9% on first $500k taxable income | ~$30k/yr if hitting threshold | **$500k limit SHARED across associated group — allocate to highest-income corp via S23** |
 | CCA Class 50 + AccII | 82.5% Y1 deduction on computers/servers | Time-value, front-loads deductions | Per-company |
-| Quick Method GST/HST | If <$400k sales, simpler method | $500–2k/yr cash if eligible | Per-company |
+| Quick Method GST/HST | If <$400k sales, simpler method | $500–2k/yr cash if eligible | **LIKELY UNAVAILABLE — Quick Method $400k threshold applies to associated-group totals; Nexa + Westin + Divine combined revenue probably exceeds limit. Re-verify with accountant.** |
 | OIDMTC (Ontario Interactive Digital Media) | If building interactive media products | 35–40% of eligible labour | Strict eligibility test; need to verify product fits |
 | Apprenticeship Job Creation TC | 10% of eligible apprentice wages, max $2k/yr per apprentice | Per apprentice hired | Activates when first apprentice T4 employee hired |
 | Intercompany cost recovery | Bill associated corps for shared services (back-office, hosting, IT) | Allocates expenses to highest-tax-rate corp | Requires arm's-length pricing documentation |
@@ -521,7 +528,8 @@ Already installed. Use for SaaS/Hosting/Support contracts: recurring invoices, S
 2. **Transfer pricing on intercompany services** — Nexa billing Westin/Divine must be at fair market value. Document hourly rate methodology and apply consistently across all clients. Penalty: 10% of any adjustment.
 3. **Past data backposting** — once accountant records arrive, mapping old transactions into new structure requires care to avoid breaking the post-2025-12-31 lock.
 4. **BC PST on software services** — BC PST exempts custom software developed for a specific customer; off-the-shelf software and certain SaaS subscriptions ARE taxable. For Nexa's mix (most work is custom dev = exempt; SaaS sold off-the-shelf to BC customers = taxable at 7%), each BC customer/product combo needs review. Default to "GST only" for custom dev; flag SaaS-to-BC for review at first sale.
-5. **Quebec QST registration** — required if Nexa has QC customers and revenue >$30k. Confirm registration status.
+5. **Quebec QST registration** — required if Nexa has QC customers and revenue >$30k. Confirm registration status. If not yet registered and you start taking QC clients, registration with Revenu Québec is separate from CRA.
+8. **HST filing cadence review** — currently annual. Once revenue clears $1.5M (combined Nexa-only, not associated group), CRA may auto-move you to **quarterly** filing. Monitor and update filing cadence in tax report config when it happens.
 6. **Specified employee SR&ED math** — Gurpreet's salary cap is 75%, no bonus inclusion. Accountant must apply at T661 time.
 7. **Multi-company Odoo (future sub-project)** — Westin and Divine currently run on separate Odoo databases (odoo-westin, odoo-mobility). Future option: migrate all three into one multi-company nexamain database to enable auto-mirrored intercompany invoices (Nexa invoices Westin → auto-creates Bill in Westin's books). Major data-migration effort; only worth it once intercompany volume justifies the effort.
 
@@ -535,6 +543,10 @@ Already installed. Use for SaaS/Hosting/Support contracts: recurring invoices, S
 - [ ] Product categories created with default accounts
 - [ ] Bank reconciliation rules created
 - [ ] Fiscal year locked at 2025-12-31
+- [ ] Company HST/BN number stored in full 15-char form (`741224877 RT0001`)
+- [ ] HST report config set to **annual filer**, fiscal-year-end Dec 31, deadline March 31
+- [ ] Westin Healthcare Inc and Divine Mobility Inc partner records created with Customer + Vendor flags, tagged `RP-Associated`
 - [ ] Test invoice flows through correctly for: ON customer (HST 13%), US customer (Zero-rated), QC customer (GST+QST)
 - [ ] Test vendor bill creates correct ITC for: Canadian vendor (HST ITC), foreign vendor (no ITC)
+- [ ] Test intercompany invoice: Nexa → Westin generates proper AR + 13% HST collected (Westin is Ontario-based)
 - [ ] Bank consolidation complete; ≤5 active bank journals