Contributions to both a traditional IRA and Roth IRA must be made by the tax filing deadline for the tax year in question, not including extensions. For example, a taxpayer who wishes to contribute to an IRA must do so prior to the federal tax filing deadline of the following year. This rule applies whether the IRA is an existing or new plan.
With respect to traditional IRAs, contributions may be deducted for that tax year if the contribution is made on account of that year. This applies both to contributions to individual plans and contributions to spousal plans.1
A postmark is evidence of the timeliness of the contribution.2