Your mobile phone is almost certainly one of your most used business tools. It is how you speak to clients, reply to emails on the go, manage your diary, and run half your business from your pocket. So the question of whether you can claim it as a business expense is completely reasonable.
The short answer is yes, you can, but the rules depend on whether you are a sole trader or a limited company director, and how much of your phone use is genuinely for business versus personal. Getting it wrong is one of the most common mistakes HMRC sees in self-employed tax returns, so it is worth understanding the rules properly.
The Core HMRC Rule: Wholly and Exclusively
The fundamental test for any business expense in the UK is whether it was incurred “wholly and exclusively” for the purpose of your trade. Most personal mobile phones fail this test in full because you use them for both work and personal purposes. That does not mean you get no deduction. It means you can claim the proportion that relates to business use.
HMRC does not expect your phone to be used 100% for business. It simply expects you to make a reasonable and honest estimate of the split and claim accordingly.
Sole Traders: How to Claim Your Mobile Phone
If you are self-employed and use your personal mobile phone partly for business, you can deduct the business-use proportion of your monthly contract or call costs from your trading income.
Step 1: Estimate your business use percentage.
Think honestly about how you use your phone. If you take around 40 calls per week and roughly 25 of those are for business, your business use is approximately 60%. If you run a business that is very active on WhatsApp with clients but also use it heavily for personal messaging, the split might be closer to 50/50.
There is no prescribed method for calculating this. HMRC expects a reasonable, consistent, and justifiable estimate. Keeping a two-week log of your calls and data usage at the start of each year to support the percentage you claim is sensible.
Step 2: Apply the percentage to your total phone costs.
If your monthly contract is £40 and your business use is 60%, you can claim £24 per month as a business expense, totalling £288 per year. This reduces your taxable profit by £288, saving you approximately £58 in income tax at the basic rate.
Step 3: Record it in your accounts.
On your Self Assessment return, phone costs go in the “telephone, fax, stationery and other office costs” box, or in software you use for bookkeeping they sit under “phone and internet” or similar categories.
What counts towards the calculation:
- Monthly contract cost (line rental and data)
- Business calls made on a pay-as-you-go basis
- Roaming charges incurred on a business trip abroad
What you cannot claim:
- The full cost if personal use is significant
- A handset purchased on a personal contract through personal funds (though see the limited company section below, where this works differently)
Limited Company Directors: A Much Better Option
If you run your business through a limited company, the rules are significantly more generous, and there is a clean way to claim 100% of your mobile phone costs without any personal tax charge.
The company pays for a business contract directly.
If your limited company takes out a mobile phone contract in the company’s name and pays for it directly, the entire cost is deductible for Corporation Tax purposes. This includes the handset cost and the monthly line rental.
Crucially, HMRC provides a specific exemption for employer-provided mobile phones. Under Section 319 of the Income Tax (Earnings and Pensions) Act 2003, one mobile phone provided by an employer to an employee (including a director) is exempt from Benefit in Kind tax, provided:
- The contract is in the company’s name
- The company pays the bill directly
- Only one phone per person is covered by the exemption
This means the company gets full Corporation Tax relief on the phone, and you personally pay no income tax or NI on it as a benefit, even though you use it privately. It is one of the cleanest tax-free benefits available to limited company directors.
What if I use my own personal phone for company business?
If the company reimburses you for business calls made on your personal phone, those reimbursements are not taxable provided they cover the additional business costs only (i.e. itemised business calls rather than a proportion of a flat-rate contract). In practice, this is harder to administer than simply having a company contract.
Second Phone Dedicated Entirely to Business
If you have a second mobile phone used 100% for business, with no personal calls, no personal social media, no family WhatsApp groups. That phone and its associated contract is 100% deductible as a business expense. HMRC will not challenge a full deduction where the business-only nature of the phone is genuine and defensible.
Many self-employed people who do significant business by phone find it worth having a dedicated business SIM or smartphone to make this clean. The full cost goes through accounts with no apportionment needed.
What About a Home Landline?
The same proportional approach applies. If you have a home landline and make business calls from it, you can claim the proportion of the line rental and call costs that relate to business. Line rental is more complex because it is a standing charge regardless of calls made, but HMRC does allow a proportion of it where business use is genuine. Most sole traders with a home office claim 50% of line rental and actual cost of business calls.
What About Broadband?
Broadband follows exactly the same logic. If you work from home and use your domestic broadband for business, you can claim a proportion of the monthly cost based on business use. Many sole traders claim 50% of their broadband bill. If you have a dedicated business broadband line, it is 100% deductible.
A Real-Life Example
Client A was a self-employed web designer working from home in Stanmore. He had been claiming nothing for his mobile phone on his Self Assessment return because he was unsure of the rules. His contract cost £45 per month.
When we reviewed his situation, he estimated that roughly 70% of his calls and data were business-related: client calls, project management apps, email, and business social media. He had never claimed a penny on his phone in two years of trading.
We amended both years’ returns to include the business-use proportion. The deduction across both years came to just over £750. At his 20% income tax rate, that was a tax saving of £150 that was already his. He had simply not known to claim it.
Frequently Asked Questions
Can I claim a new phone handset as a business expense? Yes, but the method depends on your business structure. As a sole trader, the handset is a capital purchase and goes through capital allowances rather than being deducted directly as an expense (unless you use the Annual Investment Allowance, which allows full deduction in year one). As a limited company, the company purchases the handset and claims it through the company’s capital allowances. The Section 319 exemption means no personal tax is triggered.
What if HMRC asks me to justify my phone claim? Have records ready: your monthly bills, and ideally a log or reasonable explanation of your business use percentage. A written note in your accounts records of how you arrived at the percentage is entirely sufficient. HMRC does not expect perfection. It expects honesty and consistency.
Can I claim WhatsApp calls? Yes. WhatsApp calls use data rather than call minutes, but they are business communications. They count as business use when calculating your proportion.
My employer already pays for my phone. Can I claim it again through self-employment? No. If your employer provides a phone for your employed role and you also use it for self-employment, you cannot claim it twice. The self-employment element would need to be assessed on the additional costs you personally bear.
Using your phone for business and not claiming it is leaving money on the table every year. At Your Tax Help Accountants in Stanmore, we review every client’s expense position as part of preparing their tax return, including phone, broadband, and home office costs.
Call Talha on 07478 645331, email info@yourtaxhelp.co.uk, or visit yourtaxhelp.co.uk.
Book your free 15-minute call: calendly.com/yourtaxhelp/15min
General guidance only. Not personal tax advice. Contact us for advice specific to your situation.
