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Complete UK Tax Guide 2025/26
Capital Gains Tax, Dividends & Self Assessment

SA108, SA100 - CGT (18%/24%), Section 104 Pooling, ISA/SIPP Tax Wrappers

SA108-ready Excel reports: Copy-paste values for Self Assessment
Section 104 Pooling: Correct share matching rules
Bed and Breakfast rules: 30-day matching applied
Dividend tax: Allowances and rates calculated

KEY CHANGES FOR 2024/25 & 2025/26

CGT RATE INCREASE (October 2024)

From 30 October 2024, CGT rates increased from 10%/20% to 18%/24%. The 2024-25 tax year is a split year - use SA108 Box 51 for the rate difference on disposals after 30 October.

CGT ALLOWANCE REDUCED

The CGT annual exempt amount dropped from 6,000 (2023/24) to 3,000 (2024/25 onwards). This was previously 12,300 before 2022/23.

DIVIDEND ALLOWANCE HALVED

Dividend allowance reduced from 1,000 (2023/24) to 500 (2024/25 onwards).

Capital Gains Tax (SA108)

CGT Rates 2025/26

Taxpayer Status Rate Income Threshold
Basic rate taxpayer 18% Up to 50,270 taxable income
Higher/additional rate taxpayer 24% Over 50,270 taxable income
Annual Exempt Amount 3,000 Tax-free allowance

2024-25 Split Year Warning

For the 2024-25 tax year, disposals before 30 October 2024 are taxed at 10%/20%, while disposals on or after 30 October 2024 are taxed at 18%/24%. Use SA108 Box 51 to record the additional tax due.

What's Chargeable to CGT

Taxable Assets:

  • Stocks and shares (outside ISA/SIPP)
  • ETFs (reporting fund status)
  • CFDs
  • Futures contracts
  • Options (traded and non-traded)
  • Cryptocurrency
  • Non-qualifying corporate bonds

CGT Exempt:

  • UK Government Gilts
  • T-Bills
  • Qualifying Corporate Bonds (QCBs)
  • ISA holdings
  • SIPP/pension holdings
  • Spread betting

SA108 Key Boxes

  • Box 1-14: Listed shares and securities
  • Box 15-22: Unlisted shares and securities
  • Box 23-30: Property and other assets
  • Box 51: Additional CGT due (2024-25 rate change)

Dividend Tax (SA100)

Dividend Tax Rates 2025/26

Tax Band Rate Income Threshold
Basic rate 8.75% Up to 50,270
Higher rate 33.75% 50,271 - 125,140
Additional rate 39.35% Over 125,140
Dividend Allowance 500 Tax-free

Foreign Dividend Withholding

Foreign dividends may have withholding tax applied at source. You can usually claim credit for this:

  • USA: 15% (with W-8BEN) - full credit available
  • Ireland: 25% - up to 15% creditable
  • Germany: 26.375% - up to 15% creditable

Share Matching Rules

UK Uses Different Matching Rules!

The UK does NOT use FIFO. Instead, it uses a specific matching order: Same-day โ†’ 30-day Bed & Breakfast โ†’ Section 104 Pool

Matching Priority Order

1. Same-Day Rule

Shares sold are first matched with shares bought on the same day.

2. Bed and Breakfast Rule (30 days)

Next, match with shares bought within 30 days after the sale. This prevents selling to crystallize a loss and immediately rebuying.

3. Section 104 Pool

Finally, match against the "pool" of all remaining shares. The pool tracks: Total quantity and Total cost (like average cost).

Section 104 Pool Example

Buy 100 shares @ 10 = 1,000

Buy 150 shares @ 12 = 1,800

Pool: 250 shares, 2,800 cost (11.20 avg)

Sell 100 shares @ 15 = 1,500

Cost: 100 x 11.20 = 1,120

Gain: 380

Pool after: 150 shares, 1,680 cost

Tax-Free Investments

Tax Wrappers

Wrapper Annual Limit Tax Treatment
ISA (Stocks & Shares) 20,000 No CGT, no dividend tax, no income tax
SIPP / Pension 60,000* Tax relief on contributions, tax-free growth
Lifetime ISA 4,000 25% bonus, age 18-39 to open

*Annual pension allowance; may be reduced for high earners

CGT-Exempt Assets

Fully Exempt:

  • UK Government Gilts
  • Treasury Bills (T-Bills)
  • Qualifying Corporate Bonds
  • Premium Bonds
  • National Savings products

Spread Betting:

Spread betting profits are tax-free as they're classified as gambling. However, losses cannot offset other gains.

Cryptocurrency

Crypto Tax Treatment

HMRC treats cryptocurrency as property, not currency. The same CGT rules apply:

Event Tax Treatment
Selling crypto for GBP/fiat CGT on gain
Swapping crypto for crypto CGT on gain (disposal of first crypto)
Using crypto to buy goods/services CGT on gain at point of spending
Mining income Income tax (miscellaneous income)
Staking rewards Income tax when received
Airdrops Income tax if received for services

Crypto Share Matching

The same UK share matching rules apply to crypto: Same-day โ†’ 30-day B&B โ†’ Pool. Each cryptocurrency (BTC, ETH, etc.) is tracked as a separate asset class.

Self Assessment Filing

Key Deadlines

Tax Year Paper Deadline Online Deadline Payment Due
2024/25 31 Oct 2025 31 Jan 2026 31 Jan 2026
2025/26 31 Oct 2026 31 Jan 2027 31 Jan 2027

Required Forms

  • SA100: Main tax return - dividends, interest income
  • SA101: Additional information - including non-reporting funds
  • SA108: Capital gains supplementary page - stocks, crypto, other assets
  • SA106: Foreign income - if claiming foreign tax credit relief

How Tax-Wizard Helps

Tax-Wizard generates an Excel report with values mapped to the exact SA108/SA100 boxes:

  • Section 104 pooling calculations for each security
  • Bed and breakfast matching applied automatically
  • Separate sheets for CGT Summary, SA108 details, dividends
  • Foreign tax credit calculations per country

Ready to Generate Your UK Tax Report?

Upload your broker statements and get SA108-ready reports in minutes. Section 104 pooling, B&B matching, and CGT calculations - all automated.

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