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UK Tax Tools

Self-Employment

Everything self-employed workers need to know about Self Assessment, Class 2 and Class 4 NI, and tax-efficient business structures.

Income Tax

£1,000 Trading & Property Allowance UK 2025-26: When to Claim vs File Self Assessment

How the £1,000 trading allowance and £1,000 property allowance work for side-hustlers and casual landlords, when they replace SA filing, and when claiming the allowance loses you money.

trading-allowance property-allowance side-hustle
Income Tax

HMRC Time to Pay Arrangement: How to Set Up a Self Assessment Payment Plan in 2026

Step-by-step guide to setting up an HMRC Time to Pay arrangement on Self Assessment debt under £30,000 — online self-service, interest, and what triggers a phone call instead.

hmrc time-to-pay self-assessment
Income Tax

Payment on Account 31 July 2026: How to Reduce Your POA Before HMRC Collects

Your second payment on account for 2025-26 is due 31 July 2026. How to check if you can reduce it — and the SA303 claim process — plus the interest charge on over-reductions, who typically benefits from a reduction, and avoiding unnecessary refunds.

self-assessment payment-on-account hmrc
General

Payments on Account Explained — Who Pays, How HMRC Calculates the 50/50 Split (2025-26)

HMRC requires Payments on Account (POAs) when your Self Assessment bill exceeds £1,000 and less than 80% is collected at source. Learn the trigger rules, 50/50 calculation, July 31 and January 31 deadlines, and how PAYE / CIS / dividend income each affect whether you pay POAs at all.

self-assessment payment-on-account hmrc
General

Payment on Account vs Balancing Payment — Why the January 31 Bill Is Bigger (HMRC SA)

The January 31 Self Assessment payment bundles the prior-year balancing payment plus the first POA for the current year — often 150% of last year's tax. Side-by-side worked examples for rising income, falling income, and first-year-POA shock, with the exact 50/50 + balance maths.

self-assessment payment-on-account balancing-payment
General

Starting a New Job in the UK — P45, Starter Checklist, Emergency Tax Code, and NI Continuity (2025-26)

Hand the new employer your P45 within 30 days or fill in the HMRC Starter Checklist. The wrong checklist tick triggers an emergency tax code (1257L W1/M1) that over-withholds for months. Student loan plan, NI continuity, and workplace pension auto-enrolment carry-over.

self-assessment employment P45
General

Payment on Account 31 July 2026 — Reduce Your POA Claim Before HMRC Collects (HMRC SA)

Your second payment on account for 2025-26 is due 31 July 2026. Learn when and how to reduce a POA via SA303 or the HMRC online account, the interest risk of reducing too far, and a worked example showing when a reduction is the right call.

self-assessment payment-on-account hmrc
General

UK Self Assessment Late Filing Penalty Relief 2024-25 — Reasonable Excuse & HMRC Appeal (HMRC)

Missed the 31 January 2026 Self Assessment deadline for 2024-25? Here is the full penalty ladder (£100 fixed, £10/day, 5% or £300 tiers), what counts as a reasonable excuse, how to appeal using form SA370 within 30 days, and tribunal case-law examples that succeeded and failed.

self-assessment penalties appeals
Income Tax

IR35 Off-Payroll Rules: How They Affect Your Take-Home Pay

What IR35 means for contractors, how inside vs outside status affects take-home pay, and the key factors HMRC considers in status determination.

IR35 off-payroll contractor
National Insurance

Employer NI Increase April 2025: What Businesses Need to Know

The employer National Insurance rate rose to 15% in April 2025 and the secondary threshold was cut to £5,000. Here is what this means for businesses and how the expanded Employment Allowance helps offset the cost.

national-insurance employer-ni employment-allowance
General

HMRC Interest Rates on Late Tax Payments 2025-26

HMRC charges interest on late tax payments at the Bank of England base rate plus 2.5%. Learn the current rates, how interest compounds, repayment interest on overpaid tax, and how to arrange a payment plan.

penalties deadlines self-assessment
National Insurance

How National Insurance Is Calculated in 2025-26

A clear guide to how Class 1 National Insurance is calculated for employees and employers in 2025-26, including thresholds, rates, and a worked example.

national-insurance class-1 employer-ni
General

Making Tax Digital for Income Tax: What You Need to Know for April 2026

Making Tax Digital for Income Tax Self Assessment (MTD ITSA) launches in April 2026 for sole traders and landlords earning over £50,000. Find out what quarterly reporting means for you and how to get ready.

self-employment making-tax-digital self-assessment
Pension

Is Salary Sacrifice for Pension Worth It? NI Savings, Benefits, and Trade-Offs

Salary sacrifice reduces your National Insurance bill and boosts your pension — but it can affect mortgage affordability, benefits entitlement, and state pension qualifying years. Here's what you need to know before signing up.

pension salary-sacrifice national-insurance
General

Self Assessment Deadlines for the 2025-26 Tax Year

Everything you need to know about Self Assessment deadlines for the 2025-26 tax year, including the 31 January 2027 online filing deadline, late filing penalties, and payment on account rules.

self-assessment deadlines penalties
General

Self Assessment: Who Needs to File a Tax Return?

Who must register for Self Assessment in 2025-26, common triggers including self-employment and income over £150,000, plus key deadlines and penalties.

self-assessment self-employment tax-return
General

Sole Trader vs Limited Company: Which Is More Tax-Efficient?

The tax you pay as a sole trader versus a limited company depends heavily on your profit level. This guide compares income tax and NI versus corporation tax and dividend tax, with worked examples at key income levels.

self-employment limited-company dividends
National Insurance

Are Voluntary National Insurance Contributions Worth Paying?

Filling NI gaps can significantly boost your State Pension. With Class 3 contributions costing £17.45 per week (2025/26), the payback period is under three years. This guide covers qualifying years, the ROI calculation, and the deadline to fill historical gaps.

national-insurance state-pension class-3
Income Tax

How Your Bonus Is Really Taxed in the UK (It's Not 40%)

Think your bonus is taxed at 40%? It's not — bonuses are taxed through cumulative PAYE like regular salary. Here's how it actually works and how to keep more.

bonus-tax paye national-insurance
General

CIS Explained: Deductions, Registration & Reclaiming Tax

How the Construction Industry Scheme works: 20% or 30% deduction rates, how to register as a subcontractor, and how to reclaim CIS tax overpayments from HMRC.

CIS construction subcontractors
General

Employment Allowance: Reduce Your Employer NI Bill

How the Employment Allowance works for small businesses, who qualifies, and how to claim up to £10,500 off your employer National Insurance bill in 2025/26.

employment-allowance national-insurance employer-NI
VAT

Making Tax Digital (MTD): What You Need to Know

An overview of HMRC's Making Tax Digital programme, covering MTD for VAT, Income Tax Self Assessment, and what businesses need to do to comply.

making-tax-digital MTD HMRC
National Insurance

UK National Insurance Classes 1, 2 & 4 — 2025-26 & 2026-27 Rates (HMRC)

HMRC National Insurance classes explained for 2025-26 and 2026-27: Class 1 (employed, 8%/2%), Class 2 voluntary £3.50/wk, Class 4 (self-employed, 6%/2%). Who pays each and the State Pension impact.

national-insurance class-1 class-4
National Insurance

UK Self-Employment Tax 2025-26 & 2026-27 — Class 2 & Class 4 NI (HMRC)

HMRC self-employment tax for 2025-26 and 2026-27: Class 2 voluntary £3.50/week, Class 4 at 6% (£12,570–£50,270) and 2% above, plus income tax. Payments on account and registration.

self-employment class-2-ni class-4-ni
Income Tax

Self Assessment Tax Return: Who Needs to File and How

A practical guide to the UK Self Assessment tax return system, covering who must file, key deadlines, and how to submit your return to HMRC.

self-assessment tax-return HMRC
Pension

Salary Sacrifice Pension: Save £1,000s on Tax and NI

Salary sacrifice can save you thousands in tax and National Insurance. See how it works, the real savings at each income level, and the trade-offs to watch for.

salary-sacrifice pension national-insurance
General

Take-Home Pay UK: What Deductions to Expect From Your Salary

Your gross salary and your take-home pay can look very different. This guide explains every deduction you might see on a UK payslip — income tax, National Insurance, pension, and more.

take-home-pay payslip income-tax

Related Calculators

Last updated 21 May 2026Tax year 2025-26

Data sources: HMRC (gov.uk/hmrc)

This tool is general information only, not financial advice.

Reviewed by UK Tax Tools Editorial Desk

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