Bitcoin Forum

This is kind of an odd question.
Is there a way / do any wallets support sending change to an address that is not part of that wallet?

I am assuming the answer is no, but I figured it could not hurt to ask.

I was thinking it would be a kind of simple way to save. Kind of like some credit cards round up your purchase to the next dollar and put the change in a savings account. Same basic concept, every time I buy something a bit gets dropped in an offline paper wallet.

-Dave

You could just do a pay-to-many transaction and send a few coins (or the remaining balance) to your savings address.

I personally wouldn’t do that due to fees (when you want to spend from the savings account, there will be a lot of inputs from each transaction). I would just manually send a few coins weekly/monthly and call it a day.

What tryninja suggests is what I normally do.

Just do a ptm in electrum, preview and calculate the change to send elsewhere.

I'm not sure but you might be able to click spend from in e I ectrum from a certain input, put in a ptm amount add the foreign address and hit the max button. I fiddle e with the fees too often so I haven't tried this recently.

Yeah... it's not a bad idea, per se... a sort of enforced savings system. It is just unfortunate that the technical workings of Bitcoin mean that accumulating a lot of dust on purpose like this may result in fees eating up a large percentage of the savings.

@OP, as TryNinja suggests, you'd be better off just making a more sizeable contribution to a paper wallet on a regular basis, as opposed to "collecting dust" like this.

As for the "dust" issue, pay now or pay later it costs the same. You still have to move the change in a transaction when you spend it later.

If you keep your eyes open it might actually be less as if you are saving it outside your normal hot wallet you can consolidate when fees are low.

Will probably go with the pay to many theory and see if that works for me.

Thanks everyone.

-Dave

@hcp, maybe it depends on the size of dust.

Maybe op buys a computer for 1 btc and has 1.1 as an input. The 0.1 gets sent to the foreign address and is stored there. He then has to get his lambo fixed so spends 100 btc on fixing it but gets a 10% refund because the dealership can send it on a ferry with the op and do the work there to avoid tax laws. The 10 btc op has left from a 100 btc output can then go into the foreign address too making a savings collection.

(disclosures:
1. I do not endorse tax avoidance or tax evasion of any kind. It took me 3 hours to fill in a tax return but it was still not the worst waste of three hours
2. The case studies used are completely fictitious and intentional or unintentional references to people is completely coincidental).

Holding for long periods of time might yield lower fees. Minimum at the moment is 1 sat per byte. Minimum is planned to go down by a factor of 5.

make sure to preview your transactions and double check what is happening because you have to pay the change manually to the "foreign address" and if you pay lower than remainder then you'll end up still having a change address automatically generated by the wallet and the "remainder" would be sent there which is not what you want.

What try ninja suggests is actually what I always do too... but of course, all considerations are made on the size of those outputs and I'm always aware not to create dust. Truth be told though, even a few hundred satoshis now to me is OK, as 1 sat/byte fees are all you need to confirm a transaction, and it has been for a very long time, minus the occasional periods of spikes, which only delay confirmation for a day or two max.

In fact, I even do send change out plus some consolidation whenever I can, piggybacking on a tx I need to do. This all saves on fees somehow while constantly keeping things lean. jackg's mentioned of forced savings is precisely why I try to send out change to a fixed wallet external to my spending one... my hodl wallet, basically!

Tip: I use the "!" on Electrum on my last line of pay to many to make sure every satoshi possible is cleared.

As DaveF said, although saving dust seems at first glance like a bad idea because of fees, you are always going to have to spend those fees to spend that dust (provided you are not splitting your coins up even more), whether it is one at a time as and when you use the dust from your "spending wallet", or whether it is all the fees at once when you spend all the dust in your "savings wallet". At least in the savings wallet, you can both wait until fees are low and just a set a very low fee and be happy to wait a couple of days for it to confirm - after all, if it is there just to be saved then speed isn't really an issue.

The best option overall is to select your UTXOs to keep dust to a minimum (regardless of where you are sending it), and do a bulk transfer of coins to your "savings wallet" on a monthly basis.

Size of dust? I think we'd both agree that 0.1 is not even close to being dust, let alone 10 BTC! ::)

0.00000546 is dust. I'd probably argue that anything less than 0.00020000 is approaching dust territory. In my opinion, a good rule of thumb is that any UTXO that would cost >=1% of it's own value to send (at min fee) should be considered dust.

For example, 0.00020000 BTC as a single non-SegWit UTXO in a simple non-SegWit transaction, is going to cost around 190 sats at 1 sat/byte min fee.... that's 0.95% of the value of the UTXO to send it. Granted there are savings to be made by consolidating dust, using multiple inputs in one transaction, SegWit etc. but I think in general terms it holds true.

In your example... 0.1 BTC of change would result in a UTXO that will only cost 0.0019% of it's value in fees :P


Hopefully, the dev of whatever wallet you are using has put some thought into this... and tries to use UTXOs as inputs that would result in non-dust outputs being generated in the first place.