UK Work From Home Costs Calculator

WFH Relief Comparison Guide

What's the difference between Flat Rate and Actual Costs?

HMRC provides two methods to claim working from home tax relief for employees. Flat rate: £6/week × weeks worked from home. Annual maximum (52 weeks): £312. No receipts needed. Self-assessment or P87 form. Actual costs: calculate the business proportion of gas, electricity, and other household running costs. Proportion = (rooms used for work / total rooms) × (hours working from home / total hours in week). Requires receipts and calculations. Only worth the effort if actual costs significantly exceed the flat £312/year rate, since the actual-costs method requires proper record-keeping and a proportional calculation across the whole tax year.

What's the key thing to understand about Actual Cost Calculation Method?

Step 1: calculate room proportion = work rooms / total rooms. Step 2: calculate time proportion = WFH hours per week / 168 total hours in week. Step 3: multiply all household energy costs by both proportions. Heating cost attributable to WFH: £1,200 annual heating × (1/5 rooms) × (37.5/168 hours) = £1,200 × 0.2 × 0.223 = £53.57. Electricity similarly. Total actual additional cost: often £100-200/year. For most employees: this barely exceeds the £312 flat rate for a full year. The actual costs method is rarely worth the extra paperwork for most employees given how close the figures usually are, which is why the flat rate remains the simpler and more popular choice.

What's the key thing to understand about Broadband and Phone?

Internet (broadband): if you need internet for work AND for personal use, HMRC will only allow the additional business cost. For most people: broadband would exist regardless — no additional cost attributable to WFH. Exception: if you upgraded to a faster plan specifically for work, the additional cost is claimable. Business telephone calls: actual cost of business calls only (not line rental). If employer provides a work mobile: use that, no personal phone cost claimed. These costs are generally the hardest to calculate accurately, since separating business and personal broadband use requires a reasonable and defensible estimate rather than an exact measurement.

What should I know about Self-Employed WFH?

Self-employed people (sole traders) use different rules: simplified expenses method: 25-50 hrs/month: £10. 51-100 hrs/month: £18. 101+hrs/month: £26. Annual maximum (101+ hrs/month throughout): £312. Same as the employee flat rate on an annual basis. Actual costs: calculate business proportion of all household running costs. No restriction to specific amounts. Can include: rent or mortgage interest (proportion), council tax (proportion), repairs and maintenance (proportion). More generous than the employee flat-rate allowance, since self-employed individuals can claim a genuine proportion of real household costs rather than being capped at a fixed weekly amount.

The Simplified Flat-Rate Method vs. Claiming Actual Costs

HMRC offers employees a simplified flat weekly or monthly rate they can claim for working from home without needing to keep any bills or receipts, covering a reasonable estimate of the extra household costs — additional heating, electricity, and similar running costs — incurred specifically because of working from home. Alternatively, you can claim the actual extra cost incurred, calculated by working out the proportion of your household bills attributable to your work use (commonly based on the fraction of your home's floor space used for work, multiplied by the proportion of time spent working there), which can produce a larger claim than the flat rate but requires evidence and a defensible calculation if ever queried. For most employees with modest, genuinely incremental home-working costs, the flat rate is simpler and close enough to the real figure to be the more practical choice; for those with a dedicated home office and higher actual costs, calculating actual costs can be worth the extra effort.

Why Choosing to Work From Home Matters for Eligibility

A key eligibility distinction is between being required to work from home by your employer (no suitable workplace provided, or a formal homeworking arrangement) versus simply choosing to work from home for convenience when a workplace is available. Tax relief for working-from-home costs has generally been available to employees in the former category, not those who voluntarily choose to work remotely when an office exists, which is a distinction many employees overlook when deciding whether to claim. Since the relaxed rules introduced temporarily during the pandemic have been rolled back, it's worth confirming current eligibility criteria for your specific working arrangement before assuming a claim will be accepted.

Keeping Records That Survive a Query

<p>Claiming actual home-working costs rather than the simplified flat rate shifts the burden onto you to show your workings if HMRC ever asks. That means keeping utility bills, broadband invoices and a record of the proportion of the home used for work and the proportion of time spent working there, since the calculation typically apportions a bill by both floor area and usage time rather than a single simple fraction. It's worth retaining bills for at least the current tax year plus the following one, noting how the business-use percentage was arrived at (for example, 'one room out of five used roughly 40 hours a week'), and keeping this consistent year to year unless your actual circumstances genuinely change. Claims that look like round, convenient numbers with no supporting calculation are the ones most likely to be challenged. The simplified flat rate avoids all of this record-keeping entirely, which is part of why many employees and small businesses choose it even when the actual-cost method would, in theory, yield a slightly larger claim.</p>

Reference: Simplified Flat-Rate Allowance by Hours Worked From Home

These flat rates are the simplified method and require no receipts, but they rarely come close to covering actual costs for someone working from home most of the week — they exist mainly for simplicity and for cases where the actual-cost calculation would not be worth the admin effort for a small claim.

Worked Example: Actual-Cost Claim vs the Flat Rate

An employee works from home three days a week, uses one room out of six in the house as a dedicated office, and incurs annual household bills of: electricity and gas £2,400, water £600, home insurance £350, and broadband £360 (which has an allowable business-use adjustment of its own). Apportioning electricity, gas, water and insurance by room (1/6 of the home) and by time (3 working-from-home days out of 7, since the room still has some personal use): (£2,400+£600+£350) x 1/6 x 3/7 = £3,350 x 1/6 x 3/7 = approximately £239 Broadband is apportioned differently since it is used by the whole household regardless of room, typically by estimated business-use percentage — say 20% business use: £360 x 20% = £72 Total actual-cost claim = approximately £311/year, versus a flat-rate claim at the "101+ hours" simplified band of £26 x 12 = £312/year for an employee working from home most of the month In this particular example the two methods land almost identically, which is common for a part-time home worker — the actual-cost method tends to pull ahead only for someone working from home full-time with high utility costs or a larger dedicated office space, where it is worth keeping the bills and doing the sums each year rather than defaulting to the flat rate.

Can Employees Claim If Their Employer Already Pays an Allowance

If an employer already pays a tax-free home working allowance under HMRC's agreed scheme, an employee generally cannot also separately claim tax relief on top of that for the same costs, since that would effectively provide relief twice over for the identical expense. Where an employer pays less than the maximum tax-free amount HMRC allows, or pays nothing at all, the employee may be able to claim the difference, or the full relief, themselves through a tax return or the relevant online claim form, but this depends on also meeting the underlying eligibility rules around being required to work from home rather than simply choosing to. Anyone unsure whether their employer's payment already covers the full available allowance should check their payslip and ask their employer directly before submitting a separate claim, since HMRC can query a claim that appears to duplicate relief already received through payroll.