Fintrum Inc. · internal accounting system
A double-entry accounting system for a Quebec corporation running proprietary options trading alongside software revenue. Built because generic bookkeeping handles neither the trading book nor GST/QST recovery correctly, and getting input tax attribution right has cash value from the first return.
This is a private system. The books, the working papers and the tax positions are behind a sign-in. What follows describes how it is built, not what it holds.
An entry cannot post unless it balances and has at least one line — an entry with no lines trivially sums to zero, which is the easy bug. Once posted it cannot be edited, deleted or un-posted by any code path. Corrections are reversing entries only, and posted entries are chained by SHA-256 so tampering shows even if the triggers were dropped.
QST is computed on the pre-GST base, not compounded. Rates carry validity dates — Nova Scotia moved 15% to 14% inside the first fiscal year, so a rate change is a data edit, not a code change. Zero-rated and exempt stay distinct: both charge no tax, but only zero-rated preserves recovery, and merging them forfeits refunds quietly.
Trading results sit in their own block rather than folded into revenue. It is not cosmetic — a statement reading as mostly investment income invites the specified investment business question. Both presentations produce identical net income, and a test asserts it.
Translation measures every transaction in CAD for reporting; conversion is an actual exchange. USD costs are paid from USD cash and only the residual is ever converted. Realized FX books on settlement; unrealized on revaluation, and only monetary balances are retranslated.
The first fiscal year ties to the previous system month by month. Twelve accounts agree to the cent; six differ for recorded reasons and must net to zero between themselves — which is what a presentation difference looks like, as against a difference in the numbers.
A working paper says what a return should say. The system separately records what it did say, item by item, and reports the difference per component rather than netting it — because two errors in opposite directions nearly cancel, and netting would hide both.
A command-line tool over a service layer, so a web interface is a second adapter rather than a rewrite. Amounts entered are pre-tax; the tax is computed.
Base : 1,000.00 CAD
Treatment : ZERO_RATED
Rule : Export — advisory/consulting/professional services to a non-resident
Authority : ETA Sch VI Pt V s.23
Total tax : 0.00 CADEvery determination names the rule that fired and its authority. Section 7 zero-rates services to non-residents but expressly excludes consulting, so the answer arrives under s.23 instead — and in an examination the citation is the part that matters, not the number.
The books, the generated walkthrough, the tax positions and the ruling requests are private.