Summary of Key Points
- Retirement plans are one of the few tax strategies that still require choosing, and in some cases formally establishing, a plan before a contribution is even possible.
- A SEP-IRA offers the most flexibility, since it can generally be opened and funded up until the business’s tax filing deadline, including extensions.
- A Solo 401(k) generally must be adopted by Dec 31 to allow salary deferral contributions for that year, with a narrow exception for certain sole proprietors.
- Cash balance and other defined benefit plans require actuarial work that takes months to complete, which makes them the least forgiving option if the decision waits until the fourth quarter.
- The right plan depends on income level, whether the business has employees, and how many years remain before retirement.
A retirement plan is one of the few places left in the tax code where the size of the deduction depends almost A retirement plan is one of the few places left in the tax code where the size of the deduction depends almost entirely on when the decision gets made. Wait too long, and some of the strongest options are no longer available, not because the law changed, but because the paperwork, plan documents, or actuarial work required to open a plan cannot be finished in time.
For business owners, September is close to the last reasonable point to have this conversation. Some retirement plans can still be opened well into next year and still count for this year’s return. Others need to exist on paper before Dec 31. Knowing which is which now prevents an option from disappearing later simply because the calendar ran out.
Why Retirement Plans Follow a Different Kind of Deadline
Most year-end tax planning revolves around a single date. A purchase either happens before Dec 31 or it does not. Retirement plans work differently, because the deadline depends on which type of plan is being considered and, in some cases, on what type of business is making the decision.
A plan that already exists is simple to fund. A plan that does not yet exist has to be adopted first, and adoption itself carries its own deadline that varies by plan type. That distinction is what actually determines how much time is left to act.
The SEP-IRA: The Most Forgiving Deadline
A Simplified Employee Pension, or SEP-IRA, is generally the easiest retirement plan for a business owner to open and fund. Unlike most other plans, a SEP-IRA can typically be established and funded up until the business’s tax filing deadline, including any extension, for the prior tax year.
That flexibility makes the SEP-IRA a common fallback for owners who reach the fall without having made a retirement decision yet. Contributions are employer-funded only, calculated as a percentage of compensation, and subject to an annual dollar cap that is adjusted each year and worth confirming with your CPA. The simplicity comes with a tradeoff. A SEP-IRA generally does not include an employee salary deferral option, which limits how much an owner with modest compensation can contribute compared to some other plan types.
The Solo 401(k): More Room to Save, Less Room on the Deadline
A Solo 401(k), sometimes called a one-participant 401(k), is built for a business owner with no employees other than a spouse. It combines two contribution sources, an employee salary deferral and an employer profit-sharing contribution, which often allows a higher total contribution than a SEP-IRA at the same income level, particularly for owners with moderate compensation.
The tradeoff is timing. A Solo 401(k) generally must be adopted, meaning the plan document is signed and in place, by Dec 31 to allow salary deferral contributions for that year. A narrow exception exists for certain sole proprietors under recent federal rules, but it is not something to rely on without confirming eligibility first. Our Charlotte tax preparation team can help confirm whether your business qualifies for that exception or whether the standard Dec 31 deadline applies.
Cash Balance and Defined Benefit Plans: Why the Fourth Quarter Is Already Too Late
Cash balance plans and other defined benefit plans allow far larger contributions than a SEP-IRA or Solo 401(k), which makes them attractive to business owners with high income and a shorter runway to retirement. The larger the potential contribution, the more moving parts the plan requires to get there.
These plans need a formal plan document, an actuarial calculation to determine the required contribution, and coordination with any existing 401(k) the business already sponsors. That process commonly takes several months from the first conversation to a signed, funded plan, which means a business considering one for this year needed to start the conversation well before the fourth quarter. Waiting until December to ask about a cash balance plan generally means the earliest it can realistically apply is next year.
Matching the Plan to Your Business
Choosing among these options is not just a matter of finding the largest possible deduction. Before settling on a plan, it is worth working through the following.
- Confirm whether the business has employees who would need to receive contributions under the same plan, since eligibility rules can significantly change the numbers.
- Compare SEP-IRA and Solo 401(k) contribution amounts using this year’s actual income, not an estimate from January.
- Decide whether the priority is simplicity or maximizing the deduction, since the two are not always the same plan.
- If a cash balance plan is even a possibility, start that conversation now rather than waiting for a year-end review.
- Confirm how an ongoing employer contribution obligation affects cash flow before committing to a plan that will need funding for several years.
Our financial consulting team in Charlotte can help you run these comparisons against your actual year-to-date numbers before a decision gets made by default rather than by design.
If Your Business Has Employees
Retirement plans that look straightforward for a solo owner can get more complicated once employees are added to the picture. SEP-IRAs, Solo 401(k)s intended for owner-only businesses, and cash balance plans all carry eligibility and contribution requirements that can extend to employees who meet certain age and service thresholds, not just the owner. A plan is rarely off the table once a business has staff, but the numbers, and sometimes the plan design itself, need a closer look before assuming it will work the same way it would for an owner with no employees.
North Carolina’s Treatment of Retirement Plan Contributions
Unlike bonus depreciation, which North Carolina generally requires businesses to add back and recover over several years, retirement plan contributions typically follow the same federal treatment at the state level, without a comparable addback. That makes a retirement plan one of the more straightforward year-end strategies to model, since the federal and North Carolina pictures generally line up in the year the contribution is made. It is still worth confirming this treatment applies to your specific plan and entity structure before finalizing an amount.
Frequently Asked Questions About Retirement Plan Deadlines
What happens if I do not establish a retirement plan by Dec 31?
It depends on the plan. A SEP-IRA can generally still be opened and funded up until the tax filing deadline, including extensions. A Solo 401(k) generally cannot accept salary deferral contributions for a year unless it was adopted by Dec 31, aside from the narrow exception noted above.
Can I still make a SEP-IRA contribution after the calendar year ends?
Generally, yes. SEP-IRA contributions can typically be made up until the business’s tax filing deadline, including extensions, which gives owners more flexibility than most other plan types.
Do I have to make the same retirement plan contribution every year?
Generally, no. SEP-IRA and profit-sharing contributions are typically discretionary from year to year. Salary deferrals under a Solo 401(k) and contributions to a cash balance plan follow different rules and are worth reviewing individually.
What if I already have a SEP-IRA and want to switch to a Solo 401(k)?
This is possible, but it requires planning, since existing SEP-IRA balances and plan terms need to be considered alongside the new plan. It is worth discussing timing and transition steps with your CPA before you intend to make the switch.
Deciding on a Retirement Plan While There Is Still Time to Act
A retirement plan can be one of the most effective tax strategies available to a business owner, but only if the decision is made while every option is still on the table. By the time December arrives, a SEP-IRA may still be workable, but a Solo 401(k) or a cash balance plan may already be out of reach for the year.
At Scharf Pera & Co., PLLC, we help Charlotte business owners weigh these options against their actual numbers, so the plan that gets chosen fits both this year’s tax picture and the years ahead. If you are considering a retirement plan and want to confirm which deadlines still apply to your situation, contact our team in Charlotte before the fourth quarter arrives.
