If plan language needs to be amended to reflect Windsor's broader definition of "spouse" or plan terms do not comply with the decision, plans must be amended by the end of the year or by the due date of the employer's tax return for the tax year that includes the date the amendment is first effective. 

2. Plans must also be amended to reflect any design changes made during the year. This should be done by the last day of the 2014 plan year, which, for calendar-year plans, is Dec. 31.  3. Individually designed qualified plans that fall into Cycle D, such as some multiemployer plans or plans whose employer identification number ends with 4 or 9, must be restated and resubmitted for a determination letter on or before Jan. 31. 

4. Updated summary plan descriptions (SPDs) must be provided to plan participants at least every five years if a material change was made to the plan during that five-year period. SPDs must also be provided at least once every 10 years for plans that have not changed for that period of time. 

5. The end of the year is a good time to check out plan limits for 2015, such as contribution and benefit limitations, so that they don't catch you by surprise.

For 401(k) plans 

1. First, check off all the items on the list for qualified plans.

2. For plans that have Section 401(k)/401(m) contribution safe harbors, a safe harbor notice must be sent out by Dec. 2 for calendar year plans. 

3. For plans with an automatic contribution arrangement, an eligible automatic contribution arrangement (EACA), or a qualified automatic contribution arrangement (QACA), or any combination of these, an auto enrollment notice must go out by Dec. 2 for calendar-year plans. 

4. Employers relying on the qualified default investment alternative (QDIA) safe harbor must send out annual notices of the fact by Dec. 2 for calendar-year plans.  5. Disclosure information on participant fees for designated investment alternatives in the plan must be provided annually. The initial disclosure was on Aug. 25, 2012, and that meant the next disclosure was due no later than Aug. 25, 2013. However, to allow administrators to time the release of the disclosure to coincide with other required disclosures, the Department of Labor gave plan administrators a one-time chance to change the deadline, and considered administrators to have satisfied the deadline if the 2013 fee disclosure was provided no later than 18 months after the initial disclosure on Aug. 30, 2012 — namely, by Feb. 25 of 2013.

Administrators who went ahead and satisfied the requirement for the 2013 disclosure by last August may opt to take advantage of the 18-month period to reset the date for the 2014 fee disclosure chart, so that they can align the release of the fee disclosures to coincide with other required disclosures. 

6. Participant benefit statements for defined contribution plans must be sent out at least once a year, while plans that allow participants to direct their investments must provide them at least quarterly. 

7. Annual summary reports of the data reported on Form 5500 must be provided — usually nine months after the plan-year ends. However, if the Form 5500 was filed under an extension, the summary annual report must be distributed within two months following the date on which the Form 5500 was due.  8. If employers want to add a QACA or an EACA to a plan, it can't be done midyear. So if that's on the agenda, the plan must adopt an amendment by Dec. 31 for calendar-year plans. 

9. Amendments to safe harbor plans also can't be done midyear, except under certain circumstances. So if an amendment is to be made, it must be done before year-end and, depending on what the change is, it may need to be made before the safe harbor notification is provided.