Business mobile vs personal phone for sole-trader trades
Most trades start on a personal mobile and stay there for years. That works until the same number is on the van, Google, and your mother-in-law's Christmas group. Here's how to choose.
Updated 31 July 2026
Most sole traders do fine with one number until work and personal collide. The clean upgrades are a dual-SIM or eSIM work line on one handset, or a second phone left in the van. Claim only the business share of a mixed phone, or the full cost of a work-only line. A separate number only helps if you silence it after hours and still cover live work calls when you are on the tools.
A builder who put his personal mobile on a scaffold board outside a job in Brighton still gets calls on that board's photo five years later. The number is public now. The question is not “should I ever have given it out?” It is whether the next number you publish (or keep) should be one you can mute at 7pm without going offline from your actual life.
Should you use one phone or two?
One phone, one number
£0 extra- Works when
- Simple. Customers already have the number. Fine if call volume is low and you do not mind work texts at Sunday lunch.
- Watch out
- Personal and work mixed forever. Harder to switch off. HMRC claim needs a fair business-use percentage.
Dual-SIM / eSIM on one handset
Cheap SIM-only (often from ~£6–£15/month; tariffs move)- Works when
- One device in the pouch. Separate work number for the van, Checkatrade, Google Business Profile. You can silence the work SIM after hours.
- Watch out
- Still one screen buzzing. You must actually turn the work line down when you say you will.
Second physical phone
Handset + SIM- Works when
- Clearest split. Leave the work phone in the van overnight. Cleanest 'wholly business' expense story if it is only used for work.
- Watch out
- Two things to charge. Easy to leave the work phone on silent in a drawer and miss jobs.
Can you claim a work phone on Self Assessment?
Sole traders claim allowable expenses on Self Assessment. A phone used for both kids' football WhatsApp and customer calls is mixed use: claim a fair business slice, not 100%. A second SIM or handset used only for the trade is the clean story (claim the work line in full). Keep bills. If you guess “80% business” with no basis, you are the person who hates January.
VAT-registered? A work contract with proper VAT invoices is tidier than reclaiming a slice of a personal family plan. Ask your bookkeeper once; do not rebuild your phone life around a forum thread from 2019.
How do you switch off a work number after hours?
Dual-SIM fails when both lines ring on the kitchen table at 10pm and you answer out of habit. Decide what you take after hours, put it in writing on your voicemail greeting, and set Focus modes so personal stays personal. Longer thoughts in the after-hours calls guide.
Whatever the handset setup, unanswered work calls can still divert when you are on the tools. The phone plan and the divert plan are separate decisions.
A work SIM still rings out if you're under a floor
Separate the number so you can switch off. When the work line is meant to be live and you cannot answer, Graftline can take those calls in your business name and send the job to WhatsApp. Trial it on the work divert for a week.
£79.99/month after the trial · about £2.60 a day · No commitment · cancel anytime
Work-phone questions
Can I claim my mobile on Self Assessment?
As a sole trader you claim the business proportion of costs that are wholly and exclusively for the trade. One mixed-use phone: pick a reasonable percentage and keep a note of how you worked it out (a month of itemised calls is enough for most people). A phone and contract used only for the business: you can usually claim the lot. This is plain-English guidance, not tax advice; ask your accountant if your setup is odd.
Should the work number go on the van?
Yes, if you want enquiries. Just know that a number on a van gets called at 9pm by people who saw it in traffic. Pair van livery with a plan for after-hours (voicemail script, divert, or a clear 'emergencies only' rule).
Do I need a 'business contract' from the network?
Not always. Plenty of sole traders run a consumer SIM-only as the work line. A business tariff can help with VAT invoices and account tools if you are VAT-registered, but the important part is how you use the number, not the marketing name on the brochure.
What about WhatsApp?
WhatsApp ties to a number. A separate work SIM gives you a work WhatsApp for job photos and customer chats without mixing in family groups. That alone convinces a lot of trades to go dual-SIM.