Handling UK vs US schedules about when to pay

I wrote this post in response to an earlier post.
But I cannot find that earlier post. 
Yet I think that my observations may lead to beneficial discussions.

And in that light I offer the following:
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regarding confusion about the UK tax year (when to file vs when to pay vs what time-frame am I paying for?)

I suffered from confusion for many years. And then I finally figured out:

1) The US tax year and filing/payment deadlines are simple and straight forward. (deadline to file and pay pretty much coincide)

2) the UK tax year has two totally different cycles and deadline dates:
-- filing
-- payment

There are two processes involved and I have not arrived at a way of making intuitive sense of how to combine them.
And so I resolved to let them keep their separate cycles.

First, my income and reporting cycle:
There is a cycle where by 30Jan I need to file my tax return for the tax year which ended last 5April. Example is that my return for tax year April 20 to 5 April 2025 is due 31 January 2026. (ie: the return I need to file by the end of January covers the tax year which ended in April of the prior year.)

Second, the cycle of my actually having pay my taxes: I now treat this as something similar to a credit card bill.

There is a portion of my taxes which are due on my file deadline, a portion which will be paid later in the year, and a portion which is used to balance out my under/over payments from previous years. And whether I need to pay any rebalance amount on 30Jan or the later payment.
So I may end up owing taxes for 2024 which were due in the tax year ending in 2025 and which I need to pay in 2026.

I have decided that the efforts which I would need to expend trying to keep track of what is due, when is it due, and it is last years taxes or this years taxes is more effort than I wish to expend.

So, with regard to what taxes are due and when they are due, I leave that up to HMRC to note on my account.

Instead, I focus my efforts on what taxes my actions will add to my "credit card bill" and leave it to HMRC to figure out when to bill me.

(Note that I do keep in mind that if my recent filing says I will owe £5000 in taxes, at some point I will need to pay that amount. But I leave it to HMRC to decide when it must be paid.)

Hopefully this helps

Terry
USC / UKC 2024

Yep, that is pretty much what I do. However, I file my taxes well before December 31st, sometimes in October, but wait until January before paying the balance of what I owe plus the first of the estimated taxes payments. I then pay my 2nd estimated payment in July.

For the next tax year 25/26 I expect my taxes to increase by a lot because I will have my first full year of SS payments. So I asked a tax accountant if I should increase my estimated taxes payments to avoid any HMRC penalty for under payment and she said that was not necessary, I could keep that money in a savings account ready for the large tax bill as there will be no HMRC penalty charged. HMRC will fine you for late payments but not for making estimated payments that are too low.