Self Assessment Tax Calculator (2026)
Estimate UK Self Assessment tax from employment income, self-employment profit, dividends and payments already made.
United Kingdom Calculator
Adjust Your Inputs
Move the sliders or type exact numbers. Results update instantly.
Instant Estimate
Your Results
Estimated Balance Due
£6,713
Based on your selected self assessment calculator assumptions. Try different sliders to compare scenarios.
Income Tax
£11,432
Class 4 National Insurance
£745
Dividend Tax
£536
These are planning estimates, not tax, legal or investment advice. Country rules, lender policies and tax rates can change.
How to Use the Self Assessment Calculator
Enter your initial figures
Input your primary values into the Self Assessment Calculator using the numeric fields or sliders.
Set your timeframe and rates
Configure interest rates, terms, contribution percentages, or tax assumptions.
Review instant calculations
Review the instant calculation breakdown to evaluate your financial planning scenario.
Formula & Calculation Methodology
Balance Due = Income Tax + Class 4 NI + Dividend Tax - Tax Already PaidThis calculator uses standard United Kingdom financial formulas, IRS thresholds, and amortization schedules. All results compute instantly in your browser with zero data stored or transmitted.
Calculation Examples & Scenarios
Baseline Planning Scenario
Standard United Kingdom planning inputs with default rates and values.
Key Benefits
- Instant, accurate estimates based on standard United Kingdom financial formulas
- Browser-based calculations with 100% data privacy and no signup required
- Scenario comparison by adjusting variables one at a time
Common Use Cases
- Monthly budgeting and goal planning for United Kingdom residents
- Comparing alternative financial decisions before committing funds
- Understanding the compound effect of rates and time horizons
Planning Guidance for Self Assessment Tax Calculator
When making financial decisions involving self assessment calculator, having accurate numbers is critical. Small changes in interest rates, contribution schedules, or fee structures can yield significant differences over time.
Use this calculator to test conservative and optimistic scenarios before signing contracts or reallocating investment capital. Review current local guidelines and speak with a qualified advisor for personalized strategies.
Frequently Asked Questions
No. It is a planning estimate and does not submit anything to HMRC.
No. It estimates a simple balance due before any payments on account calculation.
Related United Kingdom Calculators
Bonus Tax Calculator
Estimate UK bonus take-home pay after PAYE income tax and employee National Insurance.
CIS Calculator
Estimate Construction Industry Scheme deductions from labour income and material costs.
Contractor Tax Calculator
Estimate limited company contractor take-home pay after expenses, salary, corporation tax and dividend tax assumptions.
Dividend Tax Calculator
Estimate UK dividend tax using other income, dividend income and the dividend allowance.
NI Calculator
Estimate employee National Insurance contributions from annual salary.
PAYE Calculator
Estimate UK PAYE income tax from annual taxable pay, tax-free allowance and pay frequency.
Salary Sacrifice Calculator
Estimate take-home pay impact and tax/NI savings from salary sacrifice pension contributions.
Capital Gains Tax UK
Calculate UK Capital Gains Tax on shares, cryptocurrency, and residential property after the £3,000 annual exempt allowance.
Related United Kingdom Guides
Self Assessment Tax Calculator Guide UK
Estimate a Self Assessment balance using employment income, self-employment profit, dividends and tax already paid.
CIS Tax Deduction Guide for UK Subcontractors
Estimate Construction Industry Scheme deductions from labour income, material costs and CIS deduction rate.
Contractor and Dividend Tax Planning Guide UK
Plan limited company contractor income using salary, expenses, corporation tax and dividend tax assumptions.