30% ruling for part of the year
The ruling starts or stops mid-year, so only part of the salary period uses the tax-free reimbursement model.
The number of ruling months reduces the effective threshold and cap used in the estimate, so the result sits between full-ruling and no-ruling cases.
Compare 12 months, 6 months, and no ruling to see how much of the net gain comes from the reimbursement window.