Billing From a Multi-Year Record
When the record is also the invoice, the requirements change. What a defensible long record looks like and what it lets you do that a short one cannot.
General orientation, not legal or accounting advice.
For a tool-based version of the same discipline, review work time tracking tools. The aim is to preserve dependable evidence while keeping the ordinary recording action simple enough to repeat.
A record kept for billing has a stricter standard than one kept for self-knowledge, and over years it acquires uses beyond the invoice.
When this method depends on open spreadsheet tools, the material from LibreOffice Calc offers a helpful independent point of comparison.
The stricter standard
Contemporaneous. Written at the time, not reconstructed. In a dispute this is the distinction that matters.
Specific enough to be recognised by whoever approves it, without asking the person who commissioned the work.
Consistent in rounding, stated once and unchanged.
And retained for as long as your jurisdiction requires, which is usually longer than you would otherwise keep it.
What a long billing record gives you
Effective hourly rate on fixed-price work, calculable only after the fact and the only way to know whether such work was worth taking.
Which clients cost more than they pay, visible in the gap between hours worked and hours invoiced, and invisible in any single project.
A comparison set for quoting, which is the main commercial return and needs a couple of years to assemble.
And evidence. A contemporaneous record spanning years is a substantially stronger position in any dispute than a reconstruction.
The two-record arrangement
Covered elsewhere and worth repeating: keep the billing record and the personal record separate.
The billing record is a claim and is written to be read.
The personal one is an observation and is only useful if it is not.
Merged, the billing record acquires your self-image and the personal one acquires your caution, and both lose.
Non-billable time, tracked deliberately
The proportion of your work that is billable is the figure that determines whether your rate is right.
Over years it shows the trend: whether admin is growing, whether finding work is taking more of the year, whether a particular client type is quietly expensive.
Record the non-billable categories with the same discipline, which most people do not, and which is where the interesting findings are.
Retention specifically
Longer than the general advice in this collection.
Your jurisdiction sets a minimum for records supporting tax and invoices — commonly five to seven years — and disputes can arise late.
Keep exports, dated, and know where they are.
What a client may ask for
A breakdown, which your record should produce without editing.
If you would need to sanitise it before showing it, the problem is usually the record rather than the work, and that is worth fixing while nobody is asking.
Where long billing data becomes strategic
Rate decisions with evidence: this kind of work has taken this long, consistently, for three years.
Deciding which work to stop taking.
And knowing your own capacity honestly, which is the input to every commitment you make.
What to check
Is your billing record contemporaneous throughout?
Do you know your billable proportion, by year?
Could you produce a breakdown for a client without editing it?
And do you know what your jurisdiction requires you to retain, and for how long?
The point
Keep the billing record and the personal record separate.
Merged, the billing record acquires your self-image and the personal one acquires your caution, and both lose.
Worth adding
Record the non-billable categories with the same discipline as the billable ones.
That is where the interesting findings are and it is what most people skip.
Additionally
Retention for billing is longer than the general advice here: your jurisdiction sets a minimum for records supporting tax and invoices, and disputes arise late..
Finally
A long billing record shows which clients cost more than they pay — visible in the gap between hours worked and hours invoiced, invisible in any single project..
In summary
A billing record is contemporaneous, specific, consistently rounded and retained per your jurisdiction.
Those four are not negotiable where the record becomes an invoice.
Last word
The practice this points at is unglamorous: a small daily act, a short weekly correction, an annual read, and a written page of conventions beside the data. None of it is difficult and all of it is easy to skip, which is why most records do not reach the point where they start paying.
More in this section
These notes are about keeping a personal record for years rather than for a fortnight: durability beats accuracy, and a rough record kept for five years answers questions a perfect record of one month cannot. Tool guides are included as practical comparisons, while the underlying method remains independent of any single product. Nothing here is legal, tax or medical advice: requirements differ by jurisdiction and situation.