If you were self-employed in 2013, or even if you had some freelance income, you still have until April 15, 2014, to contribute tax-deductible money to a simplified employee pension. If you’re self-employed this year, you can start making 2014 contributions any time now, too. It’s also a good time to start organizing your receipts for business expenses to get ready to do your tax return. And if you pay quarterly estimated taxes, keep in mind that your payment was due on January 15 (the last quarterly payment for 2013).