I am currently living in Canada and have funds in a savings account with a Canadian bank. Say I decide to move back to the US, how could I move those funds to a US bank account with as little loss as possible? Is this kind of transfer taxable? FWIW I am a US citizen.
My solution when I lived in Singapore was to open an account with HSBC, who at the time also had branches in the US.
When I was home, I used the same debit card, and the bank only charged a nominal currency exchange fee (since it never had to leave their system, it was lower than had it left their system).
Another option, though slightly more costly, is to use Paypal.
A third option is to cash-out in CAD and convert to USD at a "large" institution - the larger your deposit/conversion balance, the better the rate you can get.
To the best of my knowledge, this shouldn't be taxable - presuming you've paid the taxes on it to start with, and you've been filing your IRS returns every year you've been in Canada.
Hands down, the BEST absolute way is Transferwise. Google "100 USD to CAD" or the reverse. This will give you the actual, universal exchange rate at the moment.
Now go to transferwise to initiate a transfer. The will use this EXACT rate and only add a very small fee from $3-$5 for ACH, Wire, etc..
If you used a bank, they would charge a percentage based on their exchange rate. You will pay about 4-6%. So a $500 transfer just cost you $20-$30 or MORE. Also if you have a "US Bank Account" with a Canadian bank, you still pay the inflated transfer fee and don't get the universal rate. Debit card use has a fee and a terrible exchange rate.
Transferwise is a revolutionary service and I can assure you there's no cheaper way to transfer. I'm a huge fan!
Personally, I've used OFX (previous named USForex/CanadianForex) in the past to move money from USD to CAD. This was on multiple occasions and I had no hassle each time. The amount ranged from about $100USD to upwards of $3500USD. Once you have all the banking information set up correctly in their system and you initiate the transfer, they'll call to confirm the numbers/details so that the transfer can be approved. Typically about a week to transfer everything across and I believe it was a few dollars in fees each time.
I've responded to a similar question about going from CAD to USD (linked here), so I won't copy/paste the same pros/cons list. The only thing to add is this was about a year ago, so I can't affirm that everything is just as simple as when I used it.
Another option that may be cheaper, or at least faster, would be to go through cryptocurrency exchanging. If this isn't something you've done before, it's probably not a viable option due to learning/overhead involved. This may also require multiple steps if the service doesn't let you cash in via CAD and cash out via USD. Plus, it could cause some confusion with taxes since it'd be the same as buying property in CAD and selling it in USD (legally, that's how the government sees it). Again, I'd advise against this if you're not experienced with it.