United Kingdom version
How it works
Estimate ordinary US self-employment contributions, UK Class 4/voluntary Class 2, or Irish annual self-assessed Class S PRSI. Income tax, USC, capital gains and special exemptions are separate.
This is the United Kingdom planning view, with monetary inputs and outputs in GBP. A currency label does not establish that a tax rate, construction price, coverage rule or legal limit has been verified locally. The inputs and limitations below describe the actual scope.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
4-
?profit=Annual net business profitMoney · Required · Default: 60,000
-
?voluntaryClass2=UK: elect voluntary Class 2 below the small-profits thresholdTrue or false · Optional · Default: false
-
?additional=Other independently verified contribution/additional MedicareMoney · Required · Default: 0
-
?rulesConfirmed=Country/year, contribution eligibility and additional charges verifiedTrue or false · Optional · Default: false
Outputs
3-
contributionBaseModeled contribution baseCurrency · Currency: GBP
-
contributionModeled contributionsCurrency · Primary output · Currency: GBP
-
halfDeductionUS half-SE-tax adjustment before separate limitationsCurrency · Currency: GBP
Formula
US: net earnings × Social Security/Medicare rates, subject to remaining SS wage base. UK: 2026/27 Class 4 marginal bands plus eligible voluntary Class 2. Ireland: 2026 blended Class S rate and minimum.
Calculations retain numeric precision internally. Displayed values are rounded for readability. Quantities that must be purchased as whole units are rounded up only where the formula explicitly requires it.
Read the inputs before calculating
- Annual net business profit: Enter the quantity described by the label.
- UK: elect voluntary Class 2 below the small-profits threshold: Enter the quantity described by the label. Leave this unconfirmed until you have actually checked the required condition.
- Other independently verified contribution/additional Medicare: Enter the quantity described by the label.
- Country/year, contribution eligibility and additional charges verified: Enter the quantity described by the label. Leave this unconfirmed until you have actually checked the required condition.
Reproducible worked example
The following is a fictional arithmetic example, not a local quote, a verified claimant or a market forecast. Its values are included so the formula can be checked. The form does not automatically confirm any verification checkbox.
Country/year, contribution eligibility and additional charges verified: assumed confirmed solely for this fictional demonstration
| Input | Example value |
|---|---|
| Annual net business profit | 60,000 |
| UK: elect voluntary Class 2 below the small-profits threshold | false |
| Other independently verified contribution/additional Medicare | 0 |
| Country/year, contribution eligibility and additional charges verified | true |
| Output | Calculated result |
|---|---|
| Modeled contribution base | GBP 60,000 |
| Modeled contributions | GBP 2,456.6 |
| US half-SE-tax adjustment before separate limitations | GBP 0 |
Interpreting a changed assumption
Start with one complete scenario and change only one input when diagnosing a difference. Recheck units, the period of every rate, whether an amount is recurring or one-off, and whether a cost is already included elsewhere. A larger calculated benefit is not evidence that an assumption is more likely to occur.
Limitations
- Planning calculation, not a tax return, benefit decision, credit approval or legal opinion. No eligibility is inferred from a numeric result.
- Only the stated tax year and expressly supported rule components are included. Entered amounts require independent verification.
- Tax year 2026/27: Class 4 is 6% between £12,570 and £50,270 plus 2% above. Class 2 is treated paid from £7,105; below that, an eligible voluntary election adds 52 × £3.65. Special age/status exemptions and mixed employed/self-employed annual maxima need separate assessment.
- Contribution references checked 2026-09-25.
Frequently asked questions
What does this Self-employment Contribution result represent?
Estimate ordinary US self-employment contributions, UK Class 4/voluntary Class 2, or Irish annual self-assessed Class S PRSI. Income tax, USC, capital gains and special exemptions are separate. It applies the displayed formula to your inputs; it does not infer omitted facts.
Are the starting amounts verified United Kingdom prices or legal rules?
No. Numeric defaults are illustrative unless an input or dated reference explicitly identifies a researched component. Currency is GBP; local quotes, eligibility and unsupported rules must be entered and verified separately.
What must I check before relying on the result?
Planning calculation, not a tax return, benefit decision, credit approval or legal opinion. No eligibility is inferred from a numeric result. Only the stated tax year and expressly supported rule components are included. Entered amounts require independent verification.
Can I compare or share different assumptions?
Change one assumption at a time and use the browser-local project or share controls. A shared URL contains the encoded input values; do not include information you do not wish to disclose.
Sources and reference scope
- UK income authority — retrieved 2026-09-24. Use only the expressly supported schedule components; this link does not validate unrelated taxes.
These references support only their stated scope. They are not evidence that every local rule or price needed by the master expansion has been loaded.