The tax CREDIT is only good for a max of two years, so keep that in mind. To get it, you will need to buy the plan through SHOP, the small business version of Obamacare.
You can, however, still do the thing where you reimburse your nanny for her premium (or pay it directly) with untaxed money. As long as you have only one employee, this is still legal. There are no additional credits for this besides not having to pay payroll taxes on it.
We compared the plans under the individual exchange and SHOP. The SHOP plans were better, but slightly more expensive. We ended up choosing a Gold level SHOP plan. I'm in Georgia, and my nanny is young (25), so those factors of course affected the premiums and plan offerings.