What to Include When Filing Your Personal Tax Return

Filing a personal tax return can feel stressful when you’re not sure what to include.

30-second summary: 

I’m going to show you exactly what to include in your personal tax return so you avoid mistakes, missed income, lost allowances, and HMRC penalties. 

I’ll walk through every part clearly, explain the documents you need, show you how to understand your t tax code, and share when working with a personal tax advisor in London or a tax accountant in London can save money and stress.

What Filing a Personal Tax Return Actually Means

A personal tax return is a form you submit to HMRC to show how much you earned and how much tax you should pay. Some people never need to file because their employer deals with their taxes through PAYE. 

But many people do need to file, such as the self-employed, landlords, company directors, investors, and anyone with a mixed income. When I first began helping clients, I noticed how many of them were unsure if they even needed to file. It’s more common than you might think.

I learned early in my work as a personal tax advisor, London based that confusion often starts with unclear income records. Some clients think filing means only adding wages. Others forget savings interest or small freelance work. HMRC expects every source of income to be included. Even if the amount feels small to you, it still counts.

The filing deadline is usually 31 January for online returns. If you miss it, HMRC will apply penalties. The fine starts at £100 and increases the longer the return remains outstanding. 

I’ve seen clients who waited six months and ended up owing several hundred dollars in penalties, on top of the tax they already needed to pay. Filing early is easier because there is less pressure and more time to gather documents.

So filing your personal tax return means reporting what you earned, what you spent where allowed, and what tax you owe. It’s basic on the surface, but the details matter.

Why Filing Correctly Matters

Filing correctly protects you from fines and stress. It also stops overpaying taxes. Many people assume HMRC always gets things exact, but that’s not always the case. 

I’ve seen tax codes assigned incorrectly, especially the t tax code that sometimes appears when HMRC needs more information. Incorrect tax codes can cause too much tax to be taken from your wages. If you don’t notice, you could lose money for months.

Filing correctly also helps if you apply for loans, mortgages, or grants because results from your tax return are often used to check your income. 

I once worked with a small business owner who needed a mortgage, but because his tax return had a small mistake, his income looked lower on paper. We corrected it, but it delayed his mortgage application by six weeks.

There’s also peace of mind. When you know your tax return is correct, you stop worrying about HMRC letters or surprise issues later.

I’ve worked with self-employed workers, rental property owners, consultants, and salaried employees who have side earnings. Across these different situations, one thing is always true: a correct return is less trouble later. It’s quicker to do it right the first time than to fix problems after submission.

Key Documents You’ll Need

You’ll need documents that confirm your income and expenses. These include forms like P60 and P45 if you work for an employer. Your P60 shows your total salary and tax deductions for the year. 

Your P45 is given when you leave a job and shows how much tax you’ve paid until your leaving date. If you receive benefits from work, such as a company car, fuel allowance, health coverage, or other extras, you might have a P11D, which lists taxable benefits.

If you’re self-employed, you’ll need your income records, receipts, and evidence of expenses. Many self-employed people now use digital bookkeeping apps. 

I advise this because digital records reduce the risk of losing receipts. In my work as a tax accountant London based, I always encourage clients to build the habit of recording expenses as they happen. It prevents stress later.

Landlords will need rental agreements, rent payment records, maintenance receipts, and mortgage interest statements. Rental income is one area where people forget small details. Even something like replacing a broken door handle counts as an allowable expense if it is a repair rather than an improvement.

If you have savings, you may need bank interest summaries. If you have shares, dividend statements will be necessary. Investments can add extra steps, but keeping records throughout the year removes most of the difficulty.

I’ve helped many clients who came to me in January with a box of papers. They felt overwhelmed. After sorting the papers, we realised most of the needed information could have been collected earlier in the year without stress. Organisation helps more than anything else.

Income You Must Report

Every part of your income must be included. This includes wages, self-employed earnings, rental income, savings and interest, dividends from shares, pension income, trust income, and money from abroad if you receive any.

Sometimes people forget small earnings. One client of mine did tutoring online and earned £800 from it in one year. They thought it was too small to count. 

But HMRC expects all taxable income to appear. We added it to the return, and because they also had some work-related expenses, it barely changed their final tax due, but it ensured everything was correct and clear.

If you rent a room in your home, the Rent a Room Scheme may apply. You can earn up to a certain amount tax-free under that scheme. But many people don’t mention it because they assume lodging with housemates does not count as income. It does. It’s better to report it openly.

Dividend income sometimes confuses people. If you receive dividends from owning shares in a company, it must be reported even if your broker has already taken tax. There are allowances for dividends, but reporting is still required.

Income from savings interest must also be shown. Even a small interest counts.

I’ve met many clients who worried that reporting this income would always mean more tax. Sometimes, reporting extra income makes no difference because personal allowances cover it. This is one reason I encourage people to check instead of guessing.

Common Allowances and Reliefs

Allowances help reduce how much tax you owe. Many taxpayers miss allowances, which means they pay more tax than necessary.

The personal allowance is the amount you can earn before paying tax. Most people get this automatically, but if your tax code is incorrect, it may not apply correctly. Some clients with the T tax code had their allowance suspended until HMRC confirmed more details.

There is also a marriage allowance, where one spouse can transfer a portion of their personal allowance to the other if certain conditions apply. I’ve helped couples save around £200 to £250 per year simply by applying for this allowance.

Work-related expenses matter too. These can include uniforms, travel for work (not commuting), professional fees, subscriptions to certain trade bodies, or equipment used for your job. For example, if someone works as a freelance photographer and buys lenses and memory cards, those purchases can count as expenses if they’re needed for work.

Charity donations made under Gift Aid can also reduce tax. The charity receives a boost, and you get relief. Some clients donate regularly but forget to include it in their returns, missing possible tax savings.

If you’re self-employed, capital allowances may apply to equipment, computers, tools, or vehicles used in your business.

I have seen many taxpayers miss savings of £300 to £1,200 per year simply because they assumed allowances didn’t apply to them. Asking questions often saves money.

Understanding Your T Tax Code

The T tax code shows that HMRC needs more information before confirming your correct tax allowances. It can cause changes in how much tax you pay through PAYE. If you see a t tax code on your payslip, it means your tax code is temporary or under review.

If you don’t check your tax code, you may pay too much tax. I worked with an employee who was paying £70 extra per month because of a temporary code that had not been corrected. We corrected it, and they received a refund of about £600.

Always check your tax code letters. You can view your code on your HMRC online account. If something looks wrong, speak to HMRC or a personal tax advisor London specialist who can review your status. It’s easier to correct a tax code early than to fix it later through refunds.

How a Personal Tax Advisor in London Can Help

A personal tax advisor, London-based based can help you understand your income, identify allowances you may not know about, and avoid mistakes that lead to penalties.

I’ve helped many individuals who felt overwhelmed by the return process. Sometimes people just need someone to explain what each form means. Other times, they need support in calculating taxable income accurately.

A good advisor also helps prevent overpayment of tax. In my experience, around 1 in 5 clients were paying too much before seeking help because of incorrect tax codes or missed allowances. This is real money that can make a difference in daily living.

When You Might Need Auditors in London

Auditors in London are usually needed when finances are more complex. For example, if someone owns a business, has multiple rental properties, or has income from overseas.

Sometimes HMRC requests a review, and professional auditors help ensure paperwork is correct and clear.

While many individuals do not need auditors, those who run a company or hold investments sometimes do. It adds reassurance. Auditors check records to confirm accuracy. If there is ever a question from HMRC, clean and accurate records mean quicker resolution.

When to Use a Tax Accountant London Service

A tax accountant London service is helpful when time is limited or when your tax return has several income types. Some people can handle a simple return on their own. But when income has many parts, someone who works with taxes daily can prevent errors.

A tax accountant helps organise records, calculates figures, communicates with HMRC on your behalf, and saves time. For many people, the stress avoided is as valuable as the financial savings.

Mistakes That Often Cause Delays

Common mistakes that slow the return process include missing documents, mixing personal and business expenses, forgetting small income sources, and leaving things until the last week before the deadline.

I’ve also seen people submit returns with incorrect personal details, such as changed addresses or marital status not updated.

Any of these can lead to delays, corrections, or extra tax.

How to Make Filing Faster and Easier

To make filing easier, keep records throughout the year. Use a folder or a digital app to store receipts and income notes.

Check your tax code every few months. Keep a list of income sources so nothing is forgotten. And try not to leave the return until the deadline is close.

When everything is organised, filing becomes far simpler and far quicker.

Final Thoughts and Next Step

Filing your personal tax return doesn’t have to be stressful. The key is knowing what to include, keeping records, checking your T tax code, and asking for help when needed.

If your return feels confusing or time-consuming, I can help guide you through it or complete it for you. This gives you clarity, accuracy, and peace of mind.