UK ISA (Individual Savings Account) Portfolio & Allowance Tracker
Track your UK ISA contributions, remaining annual allowance and projected growth for new contributions. Uses UK ISA subscription rules and links to HMRC guidance; intended for illustrative planning, not tax advice.
- Page updated:
- Jul 14, 2026
- Tool version:
- v1.1.0
Overview
This UK-focused ISA tracker helps you check whether a planned contribution will exceed your annual ISA subscription allowance, shows allowance usage, and projects the future value of the new contribution using compound growth assumptions.
It is based on ISA subscription principles: the annual allowance is a per-tax-year total across all ISAs you hold; you cannot subscribe more than the annual allowance in a tax year. For the latest allowance amounts and HMRC guidance, see the official HMRC pages linked below.
Results
Total contributions this tax year including this contribution
$6,000.00
Remaining ISA allowance this tax year
$14,000.00
Percent of allowance used after this contribution
30.00%
Projected value of this contribution after N years
$1,480.24
Notes (validation and guidance)
Contribution within current annual allowance. Verify carry-forward rules if applicable.
How to read the result
- What it means
- The displayed value is an estimate based on your inputs. It represents the calculated scenario under current assumptions, not a guaranteed amount.
- Calculation limits
- The model uses simplified formulas and cannot account for all variables in your specific case (local regulations, personal conditions, temporal changes).
- Next step
- Use the result as a starting point. Adjust parameters to compare scenarios and validate with a professional when needed.
Glossary+−
- ISA annual allowance
The maximum total amount you can subscribe to ISAs across all your ISA accounts in a single UK tax year.
- Subscription
A contribution or payment into an ISA account that counts towards the annual allowance.
- Compound growth
Growth calculated by applying the return rate to the balance each period, so returns themselves earn returns in subsequent periods.
Key takeaways
Use this tracker to confirm whether a planned ISA contribution fits within your current tax year allowance and to see a simple projection of that contribution's growth.
Verify the current ISA allowance with HMRC and consult a financial adviser for personalised advice.
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Worked examples
Example: Checking allowance and projecting growth
You have already contributed £5,000 this tax year. You plan to add £1,000 now. Annual ISA allowance is £20,000. Expected return 4% annually for 10 years.
Interpretation
Total contributions this tax year after adding this contribution: £6,000. Remaining allowance: £14,000. Projected value of the £1,000 contribution in 10 years at 4% p.a.: approximately £1481.
Frequently asked questions
Does this calculator replace HMRC guidance?
No. Always consult HMRC or a qualified adviser for definitive rules. This tool provides illustrative calculations based on inputs you provide.
How accurate are the projections?
Projections use a simple annual compound formula and do not account for fees, taxes on underlying investments (where applicable), irregular contributions, or inflation. Use realistic return assumptions.
Sources & references
- HM Revenue & Customs (HMRC) - ISAs: https://www.gov.uk/individual-savings-accounts
- HMRC - Help and guidance for ISAs: https://www.gov.uk/government/collections/individual-savings-accounts-isas
Quality & oversight
- Author
- Ugo Candido, MBA
- Maintained by
- Ugo Candido, MBA
- Page updated
- Jul 14, 2026
- Tool version
- v1.1.0