Re: Correctly calculate PnL when transferring between accounts

[Einar S . Idsø]

Martin,

On Mon, Apr 30, 2018 at 12:26 AM, Martin Blais  wrote:

> On Tue, Apr 24, 2018 at 4:11 AM, Martin Blais  wrote:
>>
>>> The idea is supporting a transfer like this, simply moving the Position
>>> objects from one account to another while taking advantage of the booking
>>> mechanism for a reduction is a good one. I can see it being useful. It's
>>> not supported right now. I think this type of thing would require some sort
>>> of syntax.
>>>
>>
>> Great! Would this require modifications to the core, or can it be
>> implemented through a plugin?
>>
>
> I'm not sure, but I think it may require inserting code in the booking
> algorithms.
> Best is to try it out.
>

So I'm reading up on your documentation to further my understanding and
prepare for import script development, and I came across the idea of
supporting stock splits in the booking proposal doc (
http://furius.ca/beancount/doc/proposal-booking);

"Stock splits need to be able to maintain some of the original attributes
of the position, specifically, the original trade date and the
user-specified label, if one has been provided.
This should allow a common syntax to specify an original trading lot when
reducing a position after a split."

If I understood this correctly, then this functionality would also cover
the case of moving a position from one account to another while maintaining
trading lot information for performing correct reductions, as requested
above? If so, do you have any idea if and when the stock split proposal may
be implemented?

Cheers,
Einar

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Re: Correctly calculate PnL when transferring between accounts

[Martin Blais]

On Mon, Apr 23, 2018 at 4:02 AM, Einar Idsø  wrote:

> Hi,
>
> I am a very happy user of Beancount for the past six or so months. I
> currently use it for tracking vacation hours, shares, and crypto. Since tax
> reporting is almost due, I need to properly calculate PnL for my shares and
> crypto. This becomes extremely difficult when purchasing many lots, when
> transferring lots from one broker to another and when exchanging between
> multiple currencies.
>

Crypto presents somewhat of a challenge for all these accounting systems,
because it is to be treated like an investment, tracking all the lots and
cost basis, but at the same time, users also expect to be able to spend
those instruments as if they were money with the expectations of simplicity
that counting units of a currency implies. So basically it's forcing
investment tracking to be fully automaitc, and most of these systems aren't
designed with that in mind-- tracking investments usually requires a bit of
user involvement on sales (though it's almost there).



>
> Some further elaboration:
>
> 1. I recently had to transfer some shares from one broker account to
> another in order to perform a sale. Since I have purchased shares at
> BrokerOne many times through my employer's share savings plan, I'd prefer
> to not manually enter each lot to be transferred (in my example I had
> almost 60 lots to be transferred which would create 120 painstakingly
> manually entered lines of transaction). Instead I'd like to do something
> like the following and have the transfer use FIFO to identify the lots
> transferred from BrokerOne to BrokerTwo and maintaing the cost basis *and*
> date stamp:
>
> 2000-01-01 * "Transfer shares from BrokerOne to BrokerTwo to sell at
> BrokerTwo"
>   Assets:BrokerOne -10 HOOL {}
>   Assets:BrokerTwo  10 HOOL
>

This transaction would not balance, because balancing a transaction is done
at cost, that is, the second posting would have to be in units of whatever
you bought HOOL with, e.g. USD.

The idea is supporting a transfer like this, simply moving the Position
objects from one account to another while taking advantage of the booking
mechanism for a reduction is a good one. I can see it being useful. It's
not supported right now. I think this type of thing would require some sort
of syntax. If you just wrote this:

2000-01-01 * "Transfer shares from BrokerOne to BrokerTwo to sell at
> BrokerTwo"
>   Assets:BrokerOne -10 HOOL {}
>   Assets:BrokerTwo
>

would be to insert the cost of the reduced 10 HOOL. Some sort of new syntax
would be needed to let it know that it needs to move the positions (as well
as they dates) to the interpolated account.



2000-01-02 * "Sell shares from BrokerTwo"
>   Assets:BrokerTwo-10 HOOL {} @ 12.00 USD
>   Assets:Bank 120.00 USD
>   Income:PnL
>
> The reason the date stamp would need to be maintained is so that if I had
> some shares at BrokerTwo already that were purchased after I purchased the
> shares at BrokerOne, the older shares transferred from BrokerOne would be
> the ones that were sold.
>
> 2. During crypto trading this becomes even more difficult to handle
> manually since each coin can be exchanged back and forth with a number of
> base coins such as BTC, ETH and LTC. Here we have to assign a cost basis
> and price in the local FIAT currency to each and every transaction in order
> to correctly calculate PnL. This is ok and can probably be automated from
> input scripts (I'm currently looking into that). However, there are two
> more issues for crypto trading:
> a) It is very common to transfer coins between crypto exchanges (as for my
> share example above), but due to the nature of crypto trading where trades
> happen much more frequently for different base coins, it becomes impossible
> to stay on top of which lot to transfer. One way of solving this is by
> using FIAT cost basis and price to calculate a PnL for the transfer itself
> and establish a new cost basis for the lot after the transfer. But this is
> both odd and formally wrong.
>

I agree, you should be able to just move the Position objects across
accounts. Apart from a convenient syntax to do it, there's nothing else in
Beancount's schema that should prevent making that possible and easy.



> b) If on day one I buy ETH for BTC at Binance, on day two I buy ETH for
> BTC at Poloniex, and on day three I sell ETH at Poloniex, the cost basis to
> be used for PnL calculations should really be the cost basis for the first
> ETH lot I bought, i.e. the one at Binance, and /not/ the cost basis for the
> lot at Poloniex.
>

These are in different accounts? That one is difficult.
If I understand correctly what you want to do here is treat the booking
algorithm across multiple accounts.
Beancount doesn't currently support that.
One thing you could try is to write a plugin that identifies those
cross-accounts occurrences and inserts transfers automatically, I'm not
sure if that would