Income Tax Knowledge Base

What Is Self Assessment?

How the UK system works, what it covers, and how it differs from PAYE.

Who Needs to File a Tax Return?

The complete list of people who must file — and those who don’t.

Registering for Self Assessment

How to register online, deadlines, and what information you need.

Your UTR Number

What it is, where to find it, and what to do if it’s lost.

Government Gateway

Setting up your account, verification, and two-step authentication.

Filing Your Tax Return

Step-by-step guide to completing and submitting your SA100.

Correcting Your Tax Return

How to amend mistakes after filing — and the time limits.

What Happens After Filing

HMRC processing, tax calculations, refunds, and next steps.

Employment Income & PAYE

How tax is collected from wages, benefits in kind, P45s, and P60s.

Trading Income

Self-employment profits, turnover vs profit, and the trading allowance.

Dividend Income

Dividend allowance, tax rates, and reporting on Self Assessment.

Savings Income

Personal Savings Allowance, ISAs, and interest from bank accounts.

Pension Income

Tax on State Pension, private pensions, drawdown, and annuities.

Foreign Income

Reporting overseas earnings, double taxation relief, and the remittance basis.

Cryptocurrency & Tax

CGT on crypto disposals, staking, mining, and DeFi income.

Capital Gains Tax Basics

Annual exempt amount, rates, reporting, and allowable costs.

Partnership Income

How partnerships are taxed, profit sharing, and SA800 returns.

Trust Income

Tax on trust income for beneficiaries and trustees.

State Benefits & Tax

Which benefits are taxable and which are tax-free.

Miscellaneous Income

Casual income, one-off payments, and the £1,000 trading allowance.

Registering as Self-Employed

When and how to tell HMRC you’re working for yourself.

Sole Trader vs Limited Company

Tax differences, liability, admin, and when to incorporate.

Allowable Expenses

The complete list of HMRC-recognised business deductions.

Cash Basis vs Accruals

Choosing the right accounting method for your business.

Simplified Expenses

HMRC flat rates for vehicles, working from home, and living on premises.

Claiming Losses

How to offset business losses against other income.

Basis Period Reform

The move to a tax-year basis and transitional rules.

Construction Industry Scheme

CIS registration, deductions, and monthly returns.

IR35 & Off-Payroll Working

How the off-payroll rules affect contractors and hirers.

Starting a Business & Tax

Tax essentials for new businesses from day one.

Closing a Business & Tax

Final returns, deregistration, and closing-year rules.

Property Income & MTD for Landlords

Reporting rental income, allowable expenses, and the £1,000 allowance.

Rent-a-Room Scheme

Earn up to £7,500 tax-free from letting a furnished room.

Furnished Holiday Lettings

Special tax rules, qualifying conditions, and the 2025 abolition.

Mortgage Interest Relief

The 20% tax credit for landlord finance costs.

Repairs vs Improvements

What’s deductible and what counts as capital expenditure.

Tax on Multiple Properties

One property business: pooling income, losses, and expenses.

Non-Resident Landlords

The NRLS, receiving rent gross, and filing from abroad.

CGT When You Sell Property

Rates, the 60-day rule, Private Residence Relief, and allowable costs.

Personal Allowance & Tax Bands

Current allowance, rate bands, the taper, and the 60% trap.

Marriage Allowance

Transfer £1,260 to your spouse and save up to £252 a year.

Pension Tax Relief

How relief works for basic, higher, and additional rate taxpayers.

High Income Child Benefit Charge

Thresholds, calculation, and strategies to reduce the charge.

Gift Aid

Tax relief on charitable donations for you and the charity.

Enterprise Investment Scheme

30% Income Tax relief for investing in small companies.

Venture Capital Trusts

Tax-free dividends, CGT exemption, and 30% Income Tax relief.

Working from Home Relief

Flat rates and actual costs for employed and self-employed.

Trading & Property Allowances

Earn up to £1,000 each from trading and property tax-free.

Tax-Free Childcare

Government tops up your childcare payments by 20%.

How to Pay Your Tax Bill

Every payment method, processing times, and reference numbers.

Payments on Account

Advance payments: how they’re calculated and how to reduce them.

Tax Refunds

How to check, claim, and receive overpaid tax back from HMRC.

Time to Pay Arrangements

Spread your tax bill over monthly instalments.

Tax Codes Explained

What your tax code means and how to spot errors.

HMRC Compliance Checks

What happens during a tax investigation and your rights.

Your HMRC Online Account

Personal Tax Account, Business Tax Account, and the HMRC app.

Contacting HMRC

Phone numbers, best times to call, online options, and complaints.

Authorising a Tax Agent

How to appoint an accountant to deal with HMRC on your behalf.

Starting Your First Job

Tax basics for new employees: PAYE, NI, payslips, and P60s.

Becoming Self-Employed

Your tax checklist when starting out on your own.

Employed & Self-Employed

How tax works when you have a day job and a side business.

Marriage & Tax

Tax benefits, CGT transfers, and Inheritance Tax exemptions.

Having Children & Tax

Child Benefit, HICBC, Tax-Free Childcare, and NI credits.

Retirement & Tax

Tax on pensions, the 25% lump sum, and State Pension.

Bereavement & Tax

Final returns, Inheritance Tax thresholds, and notifying HMRC.

Moving Abroad

Tax residence, the Statutory Residence Test, and split-year treatment.

Returning to the UK

Temporary non-residence rules and restarting UK tax obligations.

Side Hustles & Tax

When casual income becomes taxable and how to register.

eBay & Etsy Sellers

Trading vs personal sales, platform reporting, and expenses.

Gig Economy & Tax

Tax for Uber, Deliveroo, and TaskRabbit workers.

Airbnb Hosts

Rent-a-Room, property income rules, and platform reporting.

Content Creators & Tax

Ad revenue, sponsorships, Patreon, gifted products, and more.

Freelancers & Tax

Invoicing, expenses, and managing Self Assessment as a freelancer.

Student Loan Repayments

Plan types, thresholds, and how repayments are collected.

Digital Platform Reporting

What platforms now report to HMRC and what it means for sellers.

What Is Making Tax Digital?

The basics: what MTD is, who it affects, and key dates.

How to Sign Up for MTD

Step-by-step sign-up via Government Gateway.

MTD Deadlines

Quarterly update dates and Final Declaration deadline.

Keeping Digital Records

What HMRC requires, bridging software, and common mistakes.

MTD Quarterly Updates

What to submit, when, and how corrections work.

MTD Final Declaration

Year-end confirmation, EOPS, and adding other income.

Choosing MTD Software

Features to look for, free options, and HMRC’s approved list.

MTD Exemptions

Who is excluded and how to apply for digital exclusion.

Transitioning from SA to MTD

What changes, what stays the same, and how to prepare.

MTD Amendments & Corrections

How to fix errors in quarterly updates and final declarations.

Penalties & Interest

Points-based penalties, financial charges, and how to appeal.

National Insurance

Class 2 & 4 NI for the self-employed: rates and thresholds.

Income Tax Rates History

Current and historical rates, bands, and Scottish rates.

NI Rates History

Employee, employer, and self-employed NI rates over recent years.

Key Tax Dates Calendar

Every important deadline throughout the tax year.

HMRC Interest Rates

Late payment and repayment interest rates explained.

Mileage Allowance Rates

AMAP rates for cars, vans, motorcycles, and bicycles.

Tax Glossary

Plain-English definitions of the most common tax terms.