Recording Expenses — Repairs, Agent Fees, Insurance & More

Every pound you spend on your rental property could reduce your tax bill. Here's how to log expenses properly in RentalBux, and which costs HMRC actually allows you to claim.

Why Recording Expenses Is So Important

When HMRC calculates your tax on rental income, they don't tax the total rent you receive — they tax your profit. And profit means income minus allowable expenses.

The more accurately you record your legitimate expenses, the lower your tax bill. Miss an expense, and you're essentially overpaying tax.

RentalBux makes expense recording easy and keeps everything categorised using HMRC's approved list, so there's no guessing about whether something counts.

How to Log an Expense

Step 1: 

Go to the Accounting module from the sidebar. And Click on Invoices and Bills.

Step 2: 

Click New Bills.

Step 3: 

Enter the details:

• Amount — how much you paid

• Bill Date — date of bills issued by Vendor/Supplier

• Due Date — when you need to make payment

• Vendor/Supplier Name — who you paid (e.g., "ABC Plumbing," "Direct Line Insurance," "Smith & Co Letting Agents")

Step 4: 

Select the property this expense relates to.

Step 5: 

Choose the expense category from the Account in the dropdown. RentalBux uses HMRC's approved categories, so you'll see options like:

• Property Maintenance Costs

• Property Management Fees

• Ground Rent

• Building Insurance Expense

• Estate Agent Fees

• Real Estate Taxes

• Letting Agent Fees

• Office Rent & Utilities

Step 6: 

Attach a receipt, if available. Click Upload and select a file (PDF, image, or scan) from your device. Or if you're on mobile, use the camera to photograph the receipt.

Step 7: 

Click Save & Close.

The expense is now logged, categorised, and linked to the correct property. It will automatically feed into your income and expense calculations, your MTD quarterly summaries, and your profit-and-loss reports.

What Counts as an Allowable Expense?

HMRC allows you to deduct certain costs from your rental income. Here's a quick reference of the most common ones:

The key distinction: Repairs are allowable; improvements are not. Replacing a broken boiler with a similar one is a repair. Upgrading from a basic boiler to a top-of-the-range one could be partially treated as an improvement. If you're unsure, ask your accountant.

Attaching Receipts — Why It Matters

HMRC can ask to see proof of any expense you claim. If you can't produce a receipt, invoice, or bank statement to support the claim, they can disallow it.

By attaching receipts in RentalBux at the time you log the expense, you build a complete, searchable, time-stamped evidence trail. No more rummaging through shoeboxes at tax time.

The mobile app is particularly useful here — snap a photo of a receipt the moment you receive it, and it's filed away permanently.

How Expenses Feed Into Your MTD Calculations

Every expense you log is automatically included in your quarterly MTD summary. When your quarterly submission deadline approaches, RentalBux totals up all your expenses for that period, subtracts them from your rental income, and shows you the summary that will be sent to HMRC.

You don't need to calculate anything. Just make sure you've logged all your expenses as they happen, and the numbers take care of themselves.