[crote]

But do they have to?

In my country income taxes are automatically deducted. If you've got a single job and don't own large amounts of properties there's a decent chance your tax bill is exactly €0 and that there's no requirement for you to file.

[mnahkies]

In the UK tax on interest earned on plain savings accounts isn't deducted at source - so if you have a rainy day pot chances are you're required to register for self assessment and pay tax on it (particularly now that interest rates are higher and it's relatively easy to go above the tax free threshold, which has been frozen for a long time).

If you have investments outside of an ISA (tax free investment wrapper) then same story - you need to report disposals and dividends for tax purposes.

That's before we get into side hustles/self employment and investment properties, etc.

[pjc50]

> In the UK tax on interest earned on plain savings accounts isn't deducted at source

Yes, but as you point out you should really be using the ISA wrapper or a pension of some sort for most investments. I suspect most of those doing self assessment will either (a) be in the upper 25% of earners or (b) self-employed (~4.5m people).

It is annoying how the government has chosen to make tax slightly more annoying with "making tax digital" for self-employed people with quarterly reporting.

[awjlogan]

No, you don't have to. If you are employed through a company, stay below £100K income and don't have other income then (generally) you don't need to do a tax return - it's all handled automatically through pay as you earn payroll. However, as shown, a lot of people are self employed, want to claim deductions, have some side income etc. However, for those that do need to, it is really straightforward.