Home Use Expense Calculator

Business Use Details

How many hours is your home used for your business each day?

Used to calculate the time-based business use percentage.

How many rooms are there in your house?

Exclude bathrooms, hallways and kitchens from the room count. If your kitchen is genuinely part of an open-plan kitchen/living room, count the combined open-plan living space as one room.

How many rooms do you use wholly & exclusively for your business or part use?

Use decimals where only part of a room is used, for example 0.5. Avoid treating a room as wholly and exclusively business use unless it is genuinely never used privately.

Fixed Household Costs

Mortgage interest or rent (£ per year)

Council tax (£ per year)

Home insurance (£ per year)

Broadband (£ per year)

Other fixed costs (£ per year)

Utilities & Variable Costs

Electricity (£ per year)

Gas (£ per year)

Water (£ per year)

Repairs and maintenance (£ per year)

Only include the business-related proportion where appropriate. Repairs that relate only to private areas should not normally be included.

Cleaning (£ per year)

Other variable costs (£ per year)

Results

Total Household Costs Entered

£0.00

Room Use Percentage

Time Use Percentage

Estimated Business Use Expense

£0.00

Fixed costs entered £0.00

Variable costs entered £0.00

Overall business use percentage 0%

Estimated monthly equivalent £0.00

Calculation method: This actual-cost estimate uses: business rooms ÷ total rooms × daily business hours ÷ 24 × annual household costs. For example, 1 business room out of 5 rooms used for 8 hours per day gives an estimated business-use percentage of 6.7%.

Important: This calculator gives a simple estimate only. Actual allowable home working or business-use expenses depend on your circumstances, records, and HMRC rules.

Private Residence Relief and Capital Gains Tax: Private Residence Relief usually helps reduce or remove Capital Gains Tax when you sell your main home. However, if part of your home has been used wholly and exclusively for business, that part may not qualify for full Private Residence Relief and a portion of any gain could become liable to Capital Gains Tax. A room used partly for business and partly for normal private living is less likely to create this issue than a room permanently set aside only for business.

Room counting: Bathrooms, hallways and separate kitchens are normally excluded from the room count for this type of apportionment. If the kitchen is part of a genuine open-plan kitchen/living space, count the combined open-plan living area as one room.

Simplified expenses: Self-employed people may be able to use HMRC simplified expenses instead of calculating actual household costs. HMRC currently lists flat monthly rates based on hours worked from home: 25 to 50 hours = £10, 51 to 100 hours = £18, and 101 or more hours = £26. See HMRC guidance: simplified expenses for working from home.

HMRC also provides guidance on claiming actual costs for using your home as an office: office, property and equipment expenses.

Consider professional advice if you are unsure, especially where a room is used exclusively for business or where significant property gains may arise.