The UK tax year runs from 6 April to 5 April. That single quirk is why so many otherwise sensible budget templates fall apart for anyone self-employed in Britain: the figures you need for Self Assessment simply don't line up with January to December. Build the tracker around the tax year instead, and everything downstream — profit, mileage claims, payments on account, the 31 January deadline — falls into place.
Start with a Tax Years database
Before you log a single receipt, create a database called Tax Years. One row per year, and every other database in the workspace relates back to it. This sounds fussy. It saves hours.
Give each row these properties:
- Label — 2025/26, 2026/27 and so on.
- Start date — 6 April.
- End date — 5 April the following year.
- Filing deadline — 31 January.
- Status — In progress, Ready to file, Filed.
- Total income, Total expenses, Net profit — rollups you will set up later.
Two payoffs. Filtering any view by the current tax year becomes a one-click job rather than a date range you have to remember each April. And comparing 2024/25 with 2025/26 is instant, which is far more useful than a prettified dashboard that tells you nothing.
Two databases: income and expenses
Keep them separate. Income and expenses need different fields, different views and different habits, and merging them into one "transactions" table forces you into awkward workarounds later.
For Income: Date, Description, Client, Amount, Category (Self-employment, Employment, Other), Tax year (a relation to Tax Years), and Invoice status (Draft, Sent, Paid, Overdue). That last one matters more than it looks — a client-facing view filtered to Overdue is a gentle nudge you'll actually use.
For Expenses: Date, Supplier, Amount, Category, an Allowable checkbox, a Receipt file property, and the same Tax year relation. A sensible starting set of categories:
- Equipment and materials
- Software and subscriptions
- Travel and accommodation
- Professional fees and insurance
- Phone and internet
- Advertising and marketing
- Bank and card charges
- Training and books
Capture on the phone. Open Notion, add a row, photograph the receipt straight into the file property, set the date, done — thirty seconds at the till beats a shoebox in March. Keep records for at least five years after the 31 January filing deadline, and remember that expenses must be incurred wholly and exclusively for your business. Where a cost is partly personal, such as a phone contract, add a Business % number property and claim that share only. If the line feels blurred, ask an accountant rather than guessing; this article is general guidance, not tax advice.
Mileage that does its own maths
Mileage is the part most trackers get wrong, usually because the 10,000-mile threshold gets ignored. Using HMRC's simplified expenses rates for cars and vans, you claim 45p per mile for the first 10,000 business miles in a tax year, then 25p for every mile after that. Motorcycles are 24p and bicycles 20p.
Log each journey as a row: Date, From, To, Purpose, Miles, Vehicle. Then let the database do the arithmetic. A simple per-journey formula looks like prop("Miles") * 0.45 — roughly that shape in Notion's formula editor — but because the rate changes partway through the year, the accurate calculation belongs at tax-year level. Roll up total business miles into Tax Years, then use a formula along these lines:
if(prop("Total miles") > 10000, 10000 * 0.45 + (prop("Total miles") - 10000) * 0.25, prop("Total miles") * 0.45)
One warning: you cannot claim mileage and actual running costs for the same vehicle in the same year. Pick one method and stick to it for the whole tax year.
A deadline board for 31 January
Deadlines are the reason most people want a tracker in the first place, so give them their own small database rather than burying them in a page of notes. The dates worth having in there:
- 5 October — register for Self Assessment if you have not filed before.
- 31 October — paper return deadline.
- 31 January — online return and payment of any balancing amount, plus the first payment on account.
- 31 July — second payment on account.
Add a date property with a reminder set a fortnight ahead, and a formula such as dateBetween(prop("Deadline"), now(), "days") to show a live countdown. A card that reads "18 days" is considerably harder to ignore than a vague sense that January is ages away. If you are newly self-employed, note that payments on account are advance payments towards next year's bill, each roughly half of the previous year's liability — worth checking with an accountant before you spend the money twice.
Views and rollups that earn their keep
Three views carry most of the weight. A monthly table grouped by month, so you can see whether November was as quiet as it felt. A category breakdown grouped by expense category, which usually reveals one subscription you forgot to cancel. And a missing receipts view filtered to rows where the Receipt property is empty — the single most useful filter in the whole setup.
Ten minutes a month, or a bad week in January
Put a recurring reminder in your calendar for the first working day of each month. Reconcile the bank statement against your expenses, upload anything missing, update invoice statuses and glance at the mileage total. Ten minutes, twelve times a year.
That is the whole point of building this around the UK tax year: the tracker does the remembering, you do the brief monthly tidy-up, and January becomes an administrative afternoon rather than a panic. Start with the Tax Years database today, add the two logging databases this week, and let the rollups fill themselves in from April.