Glossary

26 tax and product terms in plain English. Every definition is one sentence, with the words people actually type underneath it.

A

Accruals basis

Recording income and expenses on the date they were earned or incurred, rather than the date the money moved.

Also typed as: traditional accounting, earned basis

Allowable expense

A cost you can deduct from rental income before tax, because it was incurred wholly and exclusively for the letting.

Also typed as: deductible, claimable, what can I claim

B

Bank feed

A read-only connection between your bank and RentalBux, so transactions arrive without you typing them in.

Also typed as: open banking, link my bank

C

Capital expenditure

Money spent improving a property rather than maintaining it. It is not deducted from rental income; it usually counts against Capital Gains Tax when you sell.

Also typed as: improvement, capex, extension

Cash basis

Recording income and expenses on the date the money actually moved. The default for most landlords.

Also typed as: money in money out

D

Digital records

Records kept in software rather than on paper. Making Tax Digital requires them.

Also typed as: digital bookkeeping, keeping records

Disallowable expense

A cost you cannot deduct from rental income — the private-use share of a bill, for example.

Also typed as: not claimable, rejected expense

F

Final Declaration

The once-a-year submission that confirms your figures are complete. It replaces the Self Assessment return you used to file each January.

Also typed as: year-end return, annual filing

Finance costs

Mortgage interest and related borrowing costs. They are not deducted as an expense; they give a reduction against your tax bill instead.

Also typed as: mortgage interest, section 24

G

Gross rents received

Total rental income before any expenses are taken off.

Also typed as: rent received, turnover, total rent

H

HMRC-recognised

Software HMRC has tested and listed as able to submit Making Tax Digital updates. RentalBux is HMRC-recognised.

Also typed as: approved, certified, on the HMRC list

J

Joint ownership

A property owned by more than one person. Each owner reports their own share of the profit.

Also typed as: co-owned, my wife owns half, shared

M

MTD ITSA

Making Tax Digital for Income Tax Self Assessment — the HMRC programme replacing the annual return with digital records and quarterly updates.

Also typed as: making tax digital, MTD

N

Net profit

What is left after allowable expenses are deducted from gross rents.

Also typed as: profit, taxable profit, bottom line

O

Obligation period

The three-month window a quarterly update covers.

Also typed as: quarter, period, reporting window

P

Profit split

The percentage of a jointly owned property’s profit that belongs to each owner.

Also typed as: share, 50/50, beneficial split

Property allowance

A flat allowance you can claim instead of deducting your actual expenses, where that works out better.

Also typed as: flat rate, allowance instead of expenses

Q

Quarterly update

A summary of your property income and expenses, sent to HMRC four times a year. It is not a bill — nothing is due to pay.

Also typed as: MTD return, quarterly filing, the four returns

R

Reconciliation

Matching a bank transaction to what it actually was, so it lands in the right category.

Also typed as: categorise, match, tidy up transactions

Repairs

Work that restores a property to its previous condition. Deductible, unlike an improvement.

Also typed as: maintenance, boiler, fixing things

Replacement of domestic items relief

Relief for replacing furniture, appliances or furnishings in a let property on a like-for-like basis.

Also typed as: wear and tear, new sofa, white goods

S

SA100

The main Self Assessment tax return form.

Also typed as: tax return, self assessment form

SA105

The part of a tax return covering UK property income. RentalBux maps your reconciled property transactions to its boxes.

Also typed as: property pages, land and property

Self Assessment

HMRC’s system for reporting income that is not taxed at source.

Also typed as: SA, doing my tax return

T

Tax year

6 April to 5 April. Written as 2026/27.

Also typed as: which year, year end

U

UTR

Your Unique Taxpayer Reference — the ten-digit number HMRC uses to identify you.

Also typed as: tax reference, ten digit number

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