*snip*
Next year, do I open a new IRA, and then convert it into the existing Roth? or do I end up with a bunch of small Roth accounts for each year?
*snip*
I have not done a backdoor Roth, but I did recently do a Roth conversion on an existing traditional IRA (both with Vanguard). I would assume the account setup issues would be similar if not the same.
I started out with:
Account A - $100 - long-standing Roth IRA with a bunch of years of contributions in it
Account B - $200 - traditional IRA, rolled from a traditional 401(k)
I submitted the conversion request, specifying I wanted the entire amount for the traditional IRA converted to a Roth (and that I wanted to pay taxes directly, without having anything withheld from my IRA amounts being converted).
This left me with:
Account A - $300 - Roth IRA
Account B - $ 0 - empty traditional rollover IRA (Vanguard has confirmed I can roll or contribute more money into this account later)
...and a tax bill for a $200 Roth conversion.
All numbers are, of course, made up.
So, I find it unlikely that you would need more than two IRA accounts per spouse (one traditional, one Roth). You wouldn't need to open a new account each year.