Self assessment idiots guide wanted

Sarahspangles

https://forums.moneysavingexpert.com/discussion/comment/81955599#Comment_81955599

If you have a spreadsheet you’re half way there. We don’t collect a full set of statements, either in print or as digital copies, though I keep any I am sent. I maintain spreadsheets with maturity date and interest paid for each tax year. If my figure didn’t match HMRC’s, or they raised a query, I’d want to see where the discrepancy was first, by requesting HMRC’s list of savings accounts. I’d then contact the specific bank or building society that was the issue and request a copy.

When my partner went onto self assessment, the bit that I found hardest to get my head round was the ‘rhythm’ of tax years and returns. You’re probably being asked to submit for 2024/25. If you’d submitted this on time ie during 2025/26, you could have asked for any tax due to be collected through your tax code in the current year ie 2026/27. You may still have that option. Once you’ve got 2024/25 under your belt, you can do 2025/26 as soon as you feel confident you’ve got the information. Any underpayment won’t have to be repaid any sooner if you do it early.

cc123mm456

A few general tips from me....

Tip 1
For some entries, the help on the online form is a little brief. To get a better understanding, I will go on to the HMRC web site, and download the PDF help pages for the paper submission. These help files are a little more detailed. Sometimes they will clarify a point that I'm stuck on.

The main forms to start with are SA100 (the paper tax return form), and SA150 (the help notes for the paper form.

Then there are separate forms and help notes for the additional pages, like foreign income, capital gains etc.

Make sure that you look up the forms and notes for the correct tax year. They are dated at the end of the tax year. So for 2024/25, you would need SA100 2025, and SA150 2025.

The online process does not use the same box numbers as the paper form. That would be too easy 😀 . So you need to check carefully that you are using the right entry box to match up. This can always be checked by saving the PDF of your completed tax return (without submitting).

Tip 2
This next tip really applies to annual submissions, after your first one for 24/25 (if that has been recently requested by HMRC). Those requests to complete a tax return for an earlier tax year will usually have a submission deadline of about 3 months.

Once the tax year has ended, I will start entering the tax return as a draft, and save the PDF reports (both of the calculation page, and the tax return page). Then leave it unsubmitted at that point.

Then throughout the year, I'll return to it a few times. This could be when some taxable income is reported late. Some examples are the end of tax year statements from investment providers, or P11D reports (of taxable benefits) from employers (which could take up to July to be produced).

I'll only submit it when I'm completely sure that everything is accurate and complete. Usually around December.

The important deadline that must not be missed is 31st January in the in the year after the tax year ends. The self-assessment must be submitted and (in some cases) payment must be made by that date.

• Edit: I'll add that there is also the option to choose to have the tax collected through PAYE in the tax year after submission. This only applies when the SA tax bill is below £3,000, and it is submitted online by 30th December. In fact that is the default option, unless you tick the box to indicate that you prefer to pay it in one go. So when the self-assessment is for 2025/2026, it will be collected through PAYE in the 2027/28 tax code, provided that it is below £3,000, submitted by 30/12/2026, and you don't choose to pay it by 31st January 2027.

Tip 3
If there is a specific entry that you don't understand, ask on the MSE forum 😀.

littlemoney

Thank you for all your comments. I will have a good read, I sure I will have more questions

Diaz09

Don't panic - it's actually quite straightforward once you get started. The most important thing is to gather everything before you begin: all your P60s, bank statements showing interest, any dividend certificates, and records of any other income like rental or freelance work. HMRC's online system walks you through each section step by step, so you won't miss anything crucial.

The key is being thorough with your records - keep everything organised in folders (digital or physical) as you'll likely need to do this annually going forward. Someone posted this a while back and it had a good breakdown of what's coming with the digital requirements: https://moneywiseuk.co.uk/making-tax-digital-2026-uk-self-employed/. Worth having a read as it explains the bigger picture of where self assessment is heading.

DRS1

https://forums.moneysavingexpert.com/discussion/comment/81964181#Comment_81964181

Well the first thing I saw when I looked at that article on MTD was a figure of £10k. Where on earth did she get that figure?

uknick

https://forums.moneysavingexpert.com/discussion/comment/81964197#Comment_81964197

From her wild imagination.

I'm pretty sure her statement that HMRC provide free MTD software is also incorrect. The only free software I'm aware they provide is Basic Payroll Tools.

For something so important it's a shame nobody fact checked her article.

DRS1

https://forums.moneysavingexpert.com/discussion/comment/81964521#Comment_81964521

Agreed. Though I think I read somewhere that HMRC are working on doing their own software option. It will be interesting to see what they come up with. It does annoy me that you have to use third party software (which may be free for a while but won't be for long) to do your taxes.

LITRG

Hi OP. We have lots of information on our website to help you with preparing your tax return. See our self assessment page here -

Self assessment and tax returns | Low Incomes Tax Reform Group

This is an older article of ours with some practical tips which will still be relevant:

Last minute tax return help! | Low Incomes Tax Reform Group

Hope this is helpful.

Langtang

Just out of interest (no pun intended) do I have to declare interest from stocks and shares that have been bought and sold, but everything was reinvested rather than being taken out? You know, if your adviser sells something to buy something else.

cc123mm456

https://forums.moneysavingexpert.com/discussion/comment/81967938#Comment_81967938

The quick answer is yes.

The longer answer:
You do not need to declare any income or capital gains for investments that are in a tax shelter (ISA or SIPP).

If the investments are in a general investment account, then any income (dividends or interest) received during the tax year must be declared, and that applies whether or not the income was reinvested.

If you hold any accumulation funds where the income is internally reinvested within the fund, you must include that income.

Usually your investment provider will provide a tax certificate after the end of the tax year with all the income details that you will need. This can take around 3 months or more to be available.

You also mentioned the scenario where your advisor sells something to buy something else.

If one of your investments is sold, that can generate a capital gain. You may or may not need to report that.
It must be reported if either of the following apply:

1. The total capital gains across the tax year exceed the CG allowance of £3,000 or
2. The total value of investments sold exceeds £50,000

It is irrelevant whether the proceeds are used to buy something else. The capital gain event occurs on the sale of an investment.