Every defined benefit plan must meet the minimum funding rules in IRC 430. The minimum required contribution is the year's normal cost plus, if assets fall short of the funding target, an installment that spreads the shortfall over 15 years. If assets exceed the funding target, the excess reduces the minimum, down to zero. The enrolled actuary calculates it with stabilized segment rates.
For a calendar 2026 plan year it is due by September 15, 2027. Quarterly installments are required only after a year with a funding shortfall, so never in a plan's first year. Missing the minimum brings a 10% excise tax on the unpaid amount, rising to 100% if it is not corrected.
The minimum is what makes a cash balance plan a commitment, because it applies in lean years too. If it exceeds a self-employed owner's earned income, the excess is not deductible that year, though it is spared the tax on nondeductible contributions. In a plan funded near its target the minimum is usually close to a full year's accrual; in a plan funded well ahead, it can fall to zero. The options when income drops, including amending or freezing the plan, are in minimum contributions and lean years.