UK investment tax calculator

UK tax calculator for Interactive Broker. To help report UK tax for dividend and capital gain.

What is included

1. Blazor WASM application ready to use.
   https://alexpung.github.io/UK-Investment-tax-calculator/

What is so special about this project?

1. It is a web app so no installation required and secure.
2. Support trades and dividends in foreign currency.
3. Support shorting and forward split corporate action. (Reverse split I need sample)
4. Implementation of TCGA92/S105 (1)(a): Multiple trades in the same day for the same Buy/Sell side is treated as a single trade. This affect same day/bread and breakfast calculation.

Supported import format and brokers

1. Interactive Brokers Flex queries only for the moment.

User can also add trades manually using the "Add trades" page.

An example is included (see below). For other brokers I suggest copying the xml example and modifying it manually if you only have small number of trades. Or if you can code new parsers are welcome.

Can broker X statements be supported?

The system is designed to accomodate new parsers of different statement files convertiable to a string (or bytestream?).
Anyone interested can implement a new parser implementing ITaxEventFileParser.
https://github.com/alexpung/UK-Investment-tax-calculator/tree/master/BlazorApp-Investment%20Tax%20Calculator/Parser/InteractiveBrokersXml

Current functionality

Parsed trade type:

1. Trades:
   1. Stock orders
   2. Future contracts (closed, not settled)
   3. Capital gain from foreign currency
2. Dividend income
   1. Dividend cash income
   2. Witholding tax paid
   3. Dividend in Lieu.
3. Corporate actions
   1. Forward split only
4. View trade calculations and dividend data in a table
5. Add dividends and trades from input of a form. (alpha: in development)

Pending implementation

More corporate actions
Export trade data. Tests and feedback are welcome, bugs are to be expected.

Output files

1. Dividend summary by year.
2. Trade summary by year and trade details.
3. Section104 histories showing changes in the pool over time.

To use:

File sample is here, you can download it and put it in the web app to see how it works.

1. You should configure the base currency of your IBKR account to GBP.
2. Configure flex query from interactive brokers. Following report required. Date format dd-MMM-yy, the date and time separator should be set to a single space.
   1. Cash Transactions: Level of detail: Detail (for dividends)
   2. Corporate actions (for stocks)
   3. Trades: Level of detail: Orders (for stocks)
   4. Statement of Funds: Level of detail: Currency (for Fx transactions)
   5. Enable "Include exchange rates" at the bottom of the setting (for Fx transactions)"
3. Download the flex query for each year in xml format using web browser.
4. Open the web application.
5. Go to the import sections and select the files, then press the "Upload" button.
6. Press "Start Calculation".
7. Export the results by pressing the buttons at the export file section.

Privacy concerns:

Your trade data is not uploaded anywhere. They never leave your browser thanks to Blazor WASM framework. The calculation is entirely done in your browser.

Design notes:

1. When a share forward or reverse split occurs it is assumed that the decimal shares will be lost (see StockSplit class). Other cases to be implemented as necessary.
2. Share matching rules are implemented according to: https://rppaccounts.co.uk/taxation-of-shares/
   1. acquisitions on the same day as the disposal
   2. acquisitions within 30 days after the day of disposal (except where made by a non-resident). Disposals are identified first with securities acquired earlier within the 30-day period after disposal – the First In First Out basis (FIFO)
   3. any shares acquired before the date of disposal which are included in an expanded ‘s. 104 holding’
   4. if the above identification rules fail to exhaust the shares disposed of, they are to be identified with subsequent acquisitions beyond the 30-day period following the disposal.

Note point #4 when buying back shorted shares #1 (same day rule) and #2 (bed&breakfast) still applies.

Example

Examples can be found in https://github.com/alexpung/UK-Investment-tax-calculator/tree/master/UnitTest/System%20Test/Interactive%20brokers

Output:

Dividend Summary

Tax Year: 2020
Region: JPN (JP)
	Total dividends: £555.00
	Total withholding tax: -£166.50
	
		Transactions:
		Asset Name: ABCD, Date: 02/02/2021, Type: Withholding Tax, Amount: -¥30,000, FxRate: 0.00555, Sterling Amount: -£166.50, Description: ABC CASH DIVIDEND - JP TAX
		Asset Name: ABCD, Date: 02/02/2021, Type: Dividend, Amount: ¥90,000, FxRate: 0.00555, Sterling Amount: £499.50, Description: ABC CASH DIVIDEND (Ordinary Dividend)
		Asset Name: ABCD, Date: 02/02/2021, Type: Payment In Lieu of a Dividend, Amount: ¥10,000, FxRate: 0.00555, Sterling Amount: £55.50, Description: ABC CASH DIVIDEND (Ordinary Dividend)

Trades Calculation

Summary for tax year 2021:
Number of disposals: 2
Total disposal proceeds: £2,693.00
Total allowable costs: £2,261.00
Total gains (excluding loss): £432.00
Total loss: £0.00

Disposal 1: Sold 200 units of ABC on 03-May-2021 for £1,834.73.	Total gain (loss): £5.56
All units of the disposals are matched with acquitions
Trade details:
	Sold 200 unit(s) of ABC on 03-May-2021 for $2,200.00 = £1,870.00 Fx rate = 0.85 with total expense £35.28, Net proceed: £1,834.73
	Expenses: Commission: $1.50 = £1.28 Fx rate = 0.85	Tax: $40.00 = £34.00 Fx rate = 0.85	
Trade matching:
Same day: Matched 50 units of the disposal. Acquition cost is £460.28
Matched trade: Bought 50 unit(s) of ABC on 03-May-2021 for $510.00 = £433.50 Fx rate = 0.85 with total expense £26.78, Total cost: £460.28
	Expenses: Commission: $1.50 = £1.28 Fx rate = 0.85	Tax: $30.00 = £25.50 Fx rate = 0.85	
Gain for this match is £458.68 - £460.28 = -£1.59



Bed and breakfast: Matched 50 units of the disposal. Acquition cost is £560.29
Matched trade: Bought 100 unit(s) of ABC on 04-May-2021 for $600.00 = £516.00 Fx rate = 0.86 with total expense £44.29, Total cost: £560.29
	Expenses: Commission: $1.50 = £1.29 Fx rate = 0.86	Tax: $50.00 = £43.00 Fx rate = 0.86	
Gain for this match is £458.68 - £560.29 = -£101.61
50 units of the earlier trade is matched with 100 units of later trade due to share split in between.

At time of disposal, section 104 contains 200 units with value £1,617.20
Section 104: Matched 100 units of the disposal. Acquition cost is £808.60
Gain for this match is £917.36 - £808.60 = £108.76

Disposal 2: Sold 100 units of DEF on 05-May-2021 for £858.71.	Total gain (loss): £427.42
All units of the disposals are matched with acquitions
Trade details:
	Sold 100 unit(s) of DEF on 05-May-2021 for $1,000.00 = £860.00 Fx rate = 0.86 with total expense £1.29, Net proceed: £858.71
	Expenses: Commission: $1.50 = £1.29 Fx rate = 0.86	
Trade matching:
Cover unmatched disposal: Matched 100 units of the disposal. Acquition cost is £431.29
Matched trade: Bought 100 unit(s) of DEF on 06-Dec-2021 for $500.00 = £430.00 Fx rate = 0.86 with total expense £1.29, Total cost: £431.29
	Expenses: Commission: $1.50 = £1.29 Fx rate = 0.86	
Gain for this match is £858.71 - £431.29 = £427.42

Section104

Section 104 detail history:
Asset Name ABC
Date		New Quantity (change)		New Value (change)
01/05/2021	200 (+200)			£1,617.20 (+£1,617.20)		
Involved trades:
Bought 200 unit(s) of ABC on 01-May-2021 for $2,000.00 = £1,600.00 Fx rate = 0.8 with total expense £17.20, Total cost: £1,617.20
	Expenses: Commission: $1.50 = £1.20 Fx rate = 0.8	Tax: $20.00 = £16.00 Fx rate = 0.8	

03/05/2021	100 (-100)			£808.60 (-£808.60)		
Involved trades:
Sold 200 unit(s) of ABC on 03-May-2021 for $2,200.00 = £1,870.00 Fx rate = 0.85 with total expense £35.28, Net proceed: £1,834.73
	Expenses: Commission: $1.50 = £1.28 Fx rate = 0.85	Tax: $40.00 = £34.00 Fx rate = 0.85	

03/05/2021	200 (+100)			£0.00 (+£0.00)		
Share adjustment on 03/05/2021 due to corporate action.

Future Contracts

    Disposal 1: Close short position 2 units of NIYH4 on 05-Mar-2023.	Total gain (loss): -£28,011.90
Trade details:
    Bought 2 unit(s) of NIYH4 on 05-Mar-2023 12:35 with contract value ¥31,000,000 with total expense £6.30
    Expenses: Commission: ¥900 = £6.30 Fx rate = 0.007	
Trade matching:
Same day: Matched 2 units of the disposal. Acquisition contract value is ¥31,000,000 and disposal contract value is ¥27,000,000
Payment made to close the contract as loss is (¥27,000,000 - ¥31,000,000) * 0.007 = -£28,000.00, added to allowable cost
Total dealing cost is £11.90
Matched trade: Sold 2 unit(s) of NIYH4 on 05-Mar-2023 12:34 with contract value ¥27,000,000 with total expense £5.60
    Expenses: Commission: ¥700 = £5.60 Fx rate = 0.008	
Gain for this match is -£28,000.00 - £11.90  = -£28,011.90

*******************************************************************************
Disposal 2: Close long position 2 units of NIYH6 on 07-Mar-2023.	Total gain (loss): -£42,009.00
Trade details:
    Sold 2 unit(s) of NIYH6 on 07-Mar-2023 12:34 with contract value ¥20,000,000 with total expense £4.80
    Expenses: Commission: ¥800 = £4.80 Fx rate = 0.006	
Trade matching:
At time of disposal, section 104 contains 2 units with contract value ¥27,000,000
Section 104: Matched 2 units of the disposal. Acquisition contract value is ¥27,000,000 and disposal contract value ¥20,000,000, proportioned dealing cost is £4.20
Payment made to close the contract as loss is (¥20,000,000 - ¥27,000,000) * 0.006 = -£42,000.00, added to allowable cost
Total dealing cost is £9.00
Gain for this match is -£42,000.00 - £9.00  = -£42,009.00

FX

    Disposal 1: Dispose 375 units of USD on 17-Dec-2019 for £285.59.	Total gain (loss): -£1.14
All units of the disposals are matched with acquisitions
Trade details:
    Dispose 375 unit(s) of USD on 17-Dec-2019 00:00 for $375.00 = £285.59 Fx rate = 0.76158. Description: Testing
Trade matching:
Bed and breakfast: 375 units of the acquisition trade against 375 units of the disposal trade. Acquisition cost is £286.74
Matched trade: Acquire 425 unit(s) of USD on 18-Dec-2019 00:00 for $425.00 = £324.97 Fx rate = 0.76463. Description: Testing 2
Gain for this match is £285.59 - £286.74 = -£1.14