Every borrowed dollar, against the use it funded
What decides whether an interest claim still stands in year fourteen is not the arithmetic. It is the record behind it — which borrowed dollar funded which use, evidenced at the time, in order, and still assemblable two decades later. That record is what ACRU keeps, and this page is what it consists of.
What does ACRU actually record?
Each draw against a credit facility, the use it funded, and the documents that evidence both — recorded as the transactions happen rather than reconstructed at year end. Interest is accrued against those uses in exact cents, and every figure carries the working paper that produced it, so a total can be opened rather than asserted.
A projection is a model; a record is evidence
Almost every tool in this category models the strategy: put in a balance, a rate, and an expected return, and it shows what the next twenty-five years might look like. That arithmetic is worth having, and this site publishes it with the assumption set printed under it. But it answers a question nobody will ever ask you.
The question you will be asked is narrower and entirely factual: this borrowed dollar — what did it buy, and when, and how do you know? The paragraph the claim is made under turns on the use borrowed money was actually put to, and the onus to trace sits with the taxpayer. A model cannot discharge it. Only a record can, and only if the record existed at the time.
What a traced record has to hold
The unit is a single draw, not a monthly balance. Each one carries the date and amount, the sub-account it came from, the account it went to, what it bought and when, the document evidencing each movement, and anything that later changed the answer. A spreadsheet holds numbers you typed; those are events that happened, with the paperwork that shows they happened, in the order they occurred.
Three properties separate the two, and none of them is about effort:
- Contemporaneity. A draw recorded the week it happened carries the statement and the trade confirmation from the same weeks. The same draw described in February of the following year carries a memory. Reviewers read those differently, and they are right to.
- Attribution, not aggregation. Interest is accrued against the uses that generated it, so what a facility cost can be split by use in exact cents rather than allocated by a percentage typed into a cell. A balance column carries no use at all.
- History that cannot be quietly rewritten. A cell edited last spring shows only what it says now. A record keeps the correction as an event alongside the original, so the question "what changed, and when did you know" has an answer that is not a memory.
What happens when the chain breaks
It usually does, and rarely for exotic reasons. Interest gets capitalised onto the line during a tight month. A draw sits in a chequing account long enough to be mixed with salary. One convenient personal purchase puts two purposes on one facility, after which every payment against it has to be split between them. A distribution turns out to be a return of capital. An investment is sold and the proceeds go somewhere other than a replacement.
Each of those is ordinary, and each is recoverable if it is caught when it happens — what makes them expensive is silence. The page on contamination works through what a mixed facility does to the arithmetic. A record built to trace flags the event at the time and keeps the split it forces, which is the difference between a fact you dealt with and a discovery someone else makes on your behalf.
Every figure opens
A total that cannot be opened is an assertion, so each one is produced with the working paper behind it: the draws that make it up, the documents that evidence them, and the assumption set and methodology version it was computed under. That is the artifact an accountant ties out — what a CPA gets at year end is a package, not a number in an email — and it is the reason the site publishes its methodology by version rather than describing it.
The boundary, stated once
ACRU computes and records. It does not characterise your tax position, and it does not give advice — the disclaimer states that in full, and it is a design constraint enforced in this repository's tests rather than an editorial habit. The records themselves are financial data about you, kept for you: how that data is handled is set out separately, and the platform does not pass any of it to a bank or a broker without an act you take deliberately.
The projection is the easy part. The records are the work.
Deductibility survives on tracing — every re-borrowed dollar tied to the investment it funded, every year closed in a form your accountant can check. Join the waitlist and we will send you a permalink to every projection you run.