Earlier quoted context omitted.
The UK has a similarly simple tax system as New Zealand. Taxes are taken out of pay every month, and that's it. Every individual gets assigned a tax code, and that tax code defines how much is taken from your pay. That tax code takes in to account how many kids you have etc. etc. The UK tends to approach tax deductions in a different way, preferring to subsidise stuff up front instead, so you never have to remember t…
Do you get any kind of deduction for giving to non-profits/charities? I give about 12-15% of my gross income to non-profits/charities every year and get a generous tax deduction for doing so. The other thing that tends to be complicated with my taxes is selling stocks. How does the UK handle things like that?
People don't tend to invest so much in stocks, instead settling for other instruments, like ISAs that already handle the tax end of things (https://en.wikipedia.org/wiki/Individual_Savings_Account). ISAs are an attempt by the UK government to encourage saving / investment by providing tax incentives to do so. Again, tax considerations done upfront vs after-the-fact.
If you do invest in stocks, you're liable for capital gains tax, just like in the US, but whether you need to file or not is dependent on how much you actually made. If you make too much, you'll have to file taxes yourself, but it's relatively straightforward.
The point is not that the system is perfect, but that it handles the case for probably >90% of the population, without stress or complications for them.