P87 Working From Home Tax Relief Explained: How HMRC Really Calculates Your Refund
Introduction
Many employees in the UK apply for P87 tax relief believing that working from home automatically entitles them to a fixed refund. In practice, HMRC applies a specific calculation framework that often produces confusing results, including refunds that seem unrelated to the bills people actually pay.
This article explains how P87 working from home tax relief is really calculated, why amounts like £312 appear repeatedly, why HMRC sometimes allows much less than expected, and when providing invoices actually helps.
The explanations below are based on real HMRC correspondence, real tax calculations, and multi-year comparisons.
What the P87 Form Is Used For
The P87 form allows PAYE employees to claim tax relief on employment expenses that were not reimbursed by their employer. For working from home, this includes additional household costs such as heating, electricity, and in limited cases broadband.
Submitting a P87 does not mean HMRC accepts the numbers you enter. It means HMRC will reassess the tax year and apply its own rules to determine what is allowable.
The Two Ways HMRC Allows Working From Home Claims
HMRC recognises two methods for working from home expenses.
The first is the standard working from home allowance. The second is claiming actual costs using a prescribed formula.
Understanding the difference is critical.
The Standard Working From Home Allowance
HMRC provides a fixed allowance of £312 per tax year for working from home. This is an expense amount, not a refund.
Key points about the £312 allowance:
It is an official HMRC allowance
It does not require invoices
It does not require calculations
It applies per tax year
It may be reduced if you did not qualify for the full year
HMRC explicitly states that if you want to claim more than £312, you must use the actual cost method.
Why £312 Is Often Misunderstood
Many people believe £312 is the refund they will receive. It is not.
£312 is the expense HMRC allows. The tax relief depends on your tax band.
If you pay basic rate tax, relief is approximately £62.
If you pay higher rate tax, relief is approximately £125.
In practice, the final refund can be higher or lower due to PAYE reconciliation, timing differences, and coding adjustments. This is why some people see refunds close to £300 even when the expense allowed is much lower.
Why HMRC Sometimes Allows Less Than £312
HMRC may reduce the allowance if you did not qualify for the full tax year.
This commonly happens when:
You changed employers during the year
You had gaps in employment
You were not required to work from home for the entire year
You had multiple employers with different work arrangements
In these cases, HMRC may pro-rate the allowance. For example, allowing £132 instead of £312.
This does not mean your bills were ignored. It means HMRC determined partial eligibility.
COVID-19 Exception for 2021–2022
For the 2021–2022 tax year, HMRC applied special pandemic rules for working from home claims. During this period, employees were allowed to claim working from home tax relief without providing evidence that their employer required remote work.
This exception existed because government guidance effectively required many employees to work from home due to COVID-19 restrictions. As a result, HMRC did not require employer confirmation or contractual wording for that year.
From the 2022–2023 tax year onwards, these pandemic concessions ended. HMRC returned to its standard position, which requires evidence that working from home was a requirement of employment. If a contract does not explicitly state remote working, HMRC might request written confirmation from the employer.
This change explains why claims for later years are more strictly assessed than those made for 2021–2022.
Claiming Actual Working From Home Costs
If you want to claim more than £312, HMRC requires a specific calculation.
The calculation works as follows:
Add up total annual utility costs such as gas and electricity
Divide by the number of countable rooms in the home
Exclude kitchens, bathrooms, and hallways
Apply the percentage of hours worked from home out of the total hours in the year
Broadband is only allowed if there was an additional cost specifically for work. If broadband was already used privately, HMRC often disallows it.
HMRC Working From Home Actual Cost Formula
To claim more than the standard working from home allowance, HMRC requires the following calculation:
Take your total annual household utility costs, including gas and electricity.
Divide this figure by the number of rooms in your home, excluding kitchens, bathrooms, and hallways.
Multiply the result by the proportion of time the room is used for work, based on the number of hours worked from home during the year.
Only this calculated amount is allowable as an employment expense.
Why High Household Bills Do Not Automatically Increase Your Claim
Even if your household bills are very high, HMRC only allows a fraction of them.
For example:
A one-bed flat usually counts as two rooms
Only one room is typically used for work
Only working hours count, not full days
When the formula is applied, the allowable expense often falls below £312, even with high bills.
This is why HMRC often advises people to use the standard allowance.
Why HMRC Often Pushes Claimants Toward the Fixed Rate
From HMRC’s perspective:
The fixed allowance is fast
It reduces disputes
It avoids complex evidence checks
It prevents overclaims
This is why HMRC letters frequently suggest using £312 unless you are confident the formula will produce a higher result.
Why Providing Invoices Does Not Guarantee a Higher Refund
Invoices only matter if you use the actual cost method. Even then:
HMRC may challenge room counts
HMRC may challenge working hours
HMRC may disallow broadband
HMRC may require employer confirmation
Invoices alone do not override HMRC’s formula.
Why Refund Amounts Look Similar Across Years
Many people notice refunds around £292 to £313 across multiple years.
This happens because:
Income levels are similar
Tax bands are similar
Expenses are similar
PAYE corrections repeat
These refunds are calculated independently for each year. They are not rolling balances or carried forward credits.
Key Takeaways
£312 is a standard HMRC working from home expense allowance
It is not a guaranteed refund
HMRC may reduce it for partial years
Actual cost claims require strict calculations and evidence
High bills do not automatically mean higher tax relief
Each tax year is calculated independently
Understanding these rules avoids unrealistic expectations and helps you choose the correct approach.
Final Advice
If you worked from home for most or all of a tax year and want simplicity, the standard allowance is usually the best option.
If you are confident your actual costs exceed £312 after HMRC’s formula, prepare calculations and evidence before claiming.
In both cases, remember that P87 triggers a reassessment. HMRC always makes the final calculation.