I've read these answers:
Can I deduct a contribution to an IRA if I also contribute to a 401(k) in the same tax year?
401K participant for part of year - Can I contribute to an IRA?
Can I contribute money to a 401k, 457b, and an IRA all at the same time?
but some of them are pretty old, some of the links are dead, and I'm not sure if any applies exactly to my situation.
My former employer offers a 401(k) plan, to which I had contributed about 60% of the annual limit when I left that job around 60% of the way through the year.
For the remaining 40% of the year I am/will not be covered by any retirement plan. Can I contribute any deductible money to my traditional IRA?
The IRS website has a page for folks covered by a retirement plan at work and a page for those who are not, but no page for a person in both categories.