Taxes are complicated, and tax form names certainly don’t help. Who’s meant to know what an SA105 Form is with a name like that, anyway?

Well, there’s method in the madness, even if it doesn’t look like it a glance; SA stands for Self Assessment, and the SA105 Form is a document that certain taxpayers need to submit alongside their yearly Self Assessment tax return in order to account for their property earnings.

However, as we move into the 2026/27 tax year, the “yearly” part of that sentence may be changing for a lot of people.  In this article, we’ll take you through all the essential details regarding the SA105 Form, including who needs to submit one, how Making Tax Digital for Income Tax (MTD ITSA) has changed the game for many, and how Crunch can help you get it sorted.

What is an SA105 Form?

The SA105 form is a supplementary page for the main SA100 tax return. Its sole purpose is to tell HMRC how much money you made from property, and what you spent on running that property. 

It covers:

• UK residential lettings (standard buy-to-lets).
• Commercial lettings (like shops, offices, or lock-ups).
• Furnished holiday Lettings (FHLs). Though the special FHL tax regime was abolished in April 2025, you still need to report the income, just without the old perks.
• Rent-a-room scheme if you earn more than the £7,500 tax-free threshold by letting out a room in your home. 

Who needs to fill in an SA105 Form?

For the 2026/27 tax year, the answer depends on your qualifying income (your total gross rent plus any self-employment turnover). This is where the new MTD ITSA rules kick in.

If your income is £50,000 or less:

You will likely continue to use the SA105 form as part of your annual Self Assessment, You’ll keep your records throughout the year and submit the form by the deadline.

If your income is over £50,000:

You are now mandated to use Making Tax Digital for Income Tax. You won't fill out a physical SA105 anymore. Instead:

• You must use HMRC-approved software to keep digital records.
• You send quarterly updates of your income and expenses to HMRC.
• You submit a "Final Declaration" at the end of the year via your software, which effectively replaces the SA105.

Note: HMRC determines if you are in the "Over £50k" group based on your 2024/25 tax return. If that return showed income over the threshold, you must be on software by 6th April 2026.

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Do I need to complete an SA105 Form if I file my Self Assessment online?

Nope – SA105 Forms are only required for those submitting Self Assessments in paper format.

If you are planning on submitting your Self Assessment in this way, we highly recommend making the switch to digital Self Assessment filings.

Not only is the process more complicated when you submit a paper tax return, but given the government’s ongoing Making Tax Digital project, we fully expect these sorts of physical submissions will be retired and moved online in the near future.

Better to get ahead of the curve and start filing digitally now. If you need any support with the transition, don’t forget to speak to our experts here at Crunch who can help you get started.

How do I complete an SA105 Form?

If it’s your first time filling in an SA105, you can download the form from the gov.uk website. If you’ve submitted one in the past, HMRC may send you one for the new tax year.

Regardless of whether you download the file or receive one in the mail, be sure to check the UK Property Notes files that HMRC makes available for each tax year; it’s an incredibly handy document for first-time filers, explaining each line of the SA105 Form and how to complete it without error.

Across the document, you’ll be asked to provide the income from all of your rental properties. This is broken up into two sections:

• In the first section, you’ll need to enter the total income you’ve earned from all Furnished Holiday Lettings you own in the UK.
• In the second section, you’ll need to provide the total rent and income you’ve earned from all other properties.

Some of the notable sections in the SA105 From include:

• Property Income Details, including the address and property type for all the rentals that you earn an income from.
• Allowable expenses, which can be deducted from the rental income for tax purposes. Check out our guide to expenses to make sure your claims are accurate and comprehensive.
• Rental income, covering your gross rental income across the tax year across all of your properties.
• Rent A Room Relief, which allows you to earn up to a threshold of £7,500 per year tax-free.
• Private Use Adjustment, which allows you to adjust your expenses if a property was used for private use at any point over the course of the tax year.

What do I need to complete my SA105 Form?

Before you start filling in your SA105, make sure you have the following information on hand:

• Your Unique Taxpayer Reference.
• All relevant information related to your UK properties, such as the number of properties you currently rent out, details relating to joint ownership, and claims for Rent A Room Relief.
• All relevant details regarding your Furnished Holidays Lets, such as your income, expenses, and any reliefs you currently claim.
• Any relevant expenses that you claim on your standard Self Assessment.

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How do I submit my SA105?

Your SA105 Form cannot be submitted alone. You’ll need to submit it alongside your Self Assessment, which you need to file each year ahead of the January 31^st deadline.

If you’re submitting paper copies of your Self Assessment to HMRC, you’ll need to post it and your SA105 Form to:

Self Assessment 

HM Revenue and Customs 

BX9 1AS 

United Kingdom

How Crunch can help

As we’ve already mentioned, you don’t need to submit an SA105 Form if you’re filing your Self Assessment tax return online. So why cause yourself the extra stress, when the friendly experts here at Crunch can handle the hard work for you?

We offer a range of accountancy packages to help support all kinds of self-employed people, including landlords. We can take the stress and complexity of Self Assessment submission out of your hands.

All you need to do is upload your documents to the software, and we’ll take care of the rest!

Don’t forget that with Making Tax Digital still rolling out across the UK economy, it’s only a matter of time before submitting physical SA105 Forms will be retired and everything will need to be completed online. Get ahead of the curve and start submitting your Self Assessments online with Crunch!

For more information, head over to our Pricing page, or give one of our friendly experts a call for a free consultation.