Working from Home Allowance: Flat Rate vs Actual Costs

If you work from home as a sole trader or freelancer, you are entitled to claim a deduction for the proportion of your household costs that relate to business use. But there are two fundamentally different ways to calculate this deduction, and choosing the wrong one could cost you hundreds of pounds per year.

HMRC offers a flat rate simplified expenses method and an actual costs method. Each has its advantages and drawbacks, and the right choice depends on your specific circumstances: how many hours you work from home, how much your household costs are, and how much record-keeping you are willing to do.

This guide compares both methods in detail, walks through the calculations, and shows you how Penny on Accounted can help you pick the most tax-efficient approach and track everything automatically.

The Flat Rate Method: HMRC Simplified Expenses

The simplified expenses scheme allows sole traders and business partnerships to claim a fixed monthly amount for working from home, based on the number of hours worked at home per month. The rates are:

| Hours worked from home per month | Flat rate per month | |----------------------------------|-------------------| | 25 to 50 hours | £10 | | 51 to 100 hours | £18 | | 101 hours or more | £26 |

These rates are set by HMRC and are designed to cover a proportion of your heating, electricity, broadband, and other household running costs. You do not need to work out the actual costs of running your home or calculate a business-use proportion. You simply count your working hours, apply the correct rate, and claim the total for the year.

How the Flat Rate Works in Practice

Let us say you work from home for 120 hours per month, every month of the year. Your annual flat rate claim would be:

• 12 months x £26 = £312 per year

If your working pattern varies, you might claim different rates in different months. For example, if you work from home for 90 hours in some months and 110 in others, you would claim £18 for the lower months and £26 for the higher months.

The flat rate method is covered in full on the GOV.UK simplified expenses page for working from home.

Advantages of the Flat Rate

• Minimal record-keeping. You only need to record your working hours, not actual household bills.
• No apportionment calculations. No need to work out what proportion of your home relates to business use.
• No risk of HMRC challenge. The rates are set by HMRC, so there is very little scope for dispute.

Disadvantages of the Flat Rate

• Often undervalues the true cost. The maximum claim is just £312 per year, even for full-time home workers with high household costs.
• No regional adjustment. Someone in central London with £2,000 monthly rent gets the same flat rate as someone in a low-cost area.
• Requires at least 25 hours per month. If you work from home for fewer than 25 hours in a given month, you cannot claim anything under the simplified scheme.

The Actual Costs Method

The actual costs method allows you to claim the genuine, proportional cost of using your home for business. This requires more work, but it often produces a significantly larger deduction.

What You Can Claim

Under the actual costs method, you can claim a business-use proportion of:

• Heating and lighting (gas and electricity)
• Water rates (if metered)
• Home insurance
• Mortgage interest (not capital repayments) or rent
• Council tax
• Broadband and telephone (the business-use proportion)
• Repairs and maintenance to the property (the business-use proportion)
• Cleaning costs (if applicable to the workspace)

Note that you cannot claim for mortgage capital repayments, and you should be cautious about claiming structural costs (such as a new roof) unless there is a clear business proportion.

How to Calculate the Business Proportion

The most common method is to use a combination of room proportion and time proportion:

Step 1: Room proportion. Count the total number of rooms in your home (excluding bathrooms, hallways, and kitchens unless they are used as workspace) and determine how many are used exclusively or mainly for business. If you use one room out of four for business, the room proportion is 25%.

Step 2: Time proportion. If you only use the room for business during certain hours, apply a further time adjustment. If you work from home 40 hours per week out of a total 168 hours in the week, the time proportion is approximately 24%.

Step 3: Combined proportion. Multiply the room proportion by the time proportion. In our example: 25% x 24% = 6%.

Some people use a simpler approach of just the room proportion without a time adjustment, which HMRC generally accepts if the room is used predominantly for business during working hours.

Worked Example: Actual Costs

Here are typical annual household costs for a sole trader in a two-bedroom flat:

| Cost | Annual amount | |-----------------------|--------------| | Gas and electricity | £2,400 | | Broadband | £480 | | Council tax | £1,800 | | Rent | £14,400 | | Home insurance | £360 | | Water rates | £420 | | Total | £19,860 |

If the business-use proportion is 15% (one room out of five used for business, adjusted for time), the actual costs claim would be:

• £19,860 x 15% = £2,979 per year

Compare this to the flat rate maximum of £312 per year, and the difference is stark. Even with a more conservative 10% business proportion, the claim would be £1,986, still more than six times the flat rate.

Advantages of Actual Costs

• Usually produces a much larger deduction. For anyone with significant household costs, the actual costs method almost always wins.
• Reflects your genuine costs. The claim is based on real expenditure, making it a fairer representation of the business cost.
• No monthly hours threshold. You can claim even if you work from home for fewer than 25 hours in some months.

Disadvantages of Actual Costs

• Heavier record-keeping. You must keep all household bills, receipts, and evidence of the apportionment basis.
• Requires a defensible calculation. HMRC may challenge your business-use proportion if it seems unreasonable.
• Capital gains tax implications. If you claim actual costs including rent or mortgage interest for a room used exclusively for business, you may lose part of your Principal Private Residence Relief when you sell the property. We discuss this risk below.

Capital Gains Tax: The Hidden Risk of Actual Costs

One concern that discourages some people from using the actual costs method is the potential impact on Capital Gains Tax (CGT) when they sell their home.

Your main residence is normally exempt from CGT under Principal Private Residence Relief. However, if part of your home is used exclusively for business, that proportion may not qualify for the relief, meaning you could face a CGT bill on the gain attributable to the business area when you sell.

The key word is "exclusively." If the room you use for business is also used for personal purposes (for instance, it doubles as a guest bedroom or the family uses it in the evenings), HMRC generally accepts that the room is not exclusively business and the CGT exemption is not affected. Most home workers fall into this category. However, if you have built a dedicated home office with no personal function, seek advice on the CGT implications before selling your home.

Employed vs Self-Employed: Different Rules

The rules for claiming home working expenses differ depending on your employment status. Self-employed individuals can use either the flat rate or actual costs method as described in this guide, claimed on the Self Assessment tax return.

Employed individuals can only claim tax relief if their employer requires them to work from home (not merely allows it). The relief is typically a flat rate of £6 per week (£312 per year) through form P87, without needing evidence of actual costs. Alternatively, employees can claim actual additional costs with supporting evidence.

The GOV.UK page on tax relief for employees working at home sets out the rules for employed individuals. If you are both employed and self-employed, you may be able to claim under both regimes, but take care not to double-count.

Which Method Should You Choose?

The answer depends on your specific circumstances, but here is a general guide:

Choose the flat rate if your household costs are low, you work from home only part-time, you want minimal record-keeping, or the difference between the two methods is small for your profit level.

Choose actual costs if your household costs are significant (especially if you rent or have a large mortgage), you work from home regularly or full time, and you are willing to keep household bills and calculate the business proportion.

For most full-time sole traders with typical UK household costs, the actual costs method will produce a materially larger deduction. The flat rate is best suited for those who work from home occasionally or who prioritise simplicity.

Once You Choose, Can You Switch?

Yes, but you cannot switch between flat rate and actual costs partway through a tax year. You can, however, change your method from one tax year to the next. Just make sure you have the records to support the actual costs claim from the start of the new tax year.

How Penny Tracks Your Home Working Costs

Whether you choose the flat rate or actual costs, Penny makes tracking effortless.

For the flat rate method: send Penny a WhatsApp message like "Worked from home 110 hours this month," and she applies the correct rate and adds it to your expenses.

For the actual costs method: Penny monitors your recurring household bills through your bank feed, calculates the business proportion based on your parameters, and updates the claim automatically as new bills come in.

You can review your claims at any time through the Accounted features dashboard. Penny also compares both methods at year end, so you can see which approach would have saved you more and plan accordingly.

If you are claiming other common sole trader deductions, our guide on tax deductions for sole traders covers the full range of expenses you should be aware of, from home office costs to travel, insurance, and professional subscriptions.

Key Takeaways

Working from home is one of the most commonly under-claimed expenses for sole traders in the UK. Here is what you need to remember:

• The flat rate method is simple but caps at £312 per year, which undervalues the true cost for most full-time home workers.
• The actual costs method usually produces a much larger deduction, often several times the flat rate, but requires more record-keeping.
• Be mindful of the CGT implications if a room is used exclusively for business, though this affects relatively few people.
• Employed and self-employed individuals have different rules and relief levels.
• You can switch methods between tax years, giving you flexibility to optimise each year.
• Penny tracks your home working costs automatically, whether you use the flat rate or actual costs, and compares both methods so you always pick the most tax-efficient approach.

Do not leave money on the table. If you work from home and are not claiming the right amount, you could be overpaying tax by hundreds of pounds each year. Sign up for Accounted and let Penny ensure you are claiming every penny you are entitled to.

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