We're already into the third month of the 2016 tax year. So isn't it too late to reduce the amount of taxes you owe for 2015? Well, no, it isn't. The tax law lets you take certain actions after the end of the year, but these are limited, and you have to act soon. The following write-offs will reduce your taxable income – and therefore lower your tax liability.

If you are working but aren't covered by a qualified retirement plan, such as a 401(k) plan at work – or, if covered, your income is below a certain amount – you can make a tax-deductible contribution to an IRA. This rule only applies if you are younger than 70½, even if you are still working.

The deduction limit for 2015 is $5,500, or $6,500 if you were at least 50 years old by the end of 2015 – although it can't be more than your earned income from a job or self-employment. If you have a nonworking spouse under age 70½ and enough earned income, you can make a deduction to the spouse's IRA (technically this is called a Kay Bailey Hutchison Spousal IRA), effectively doubling your tax deduction and retirement savings.

You must set up and add funds to your IRA by April 18, 2016 (April 19, if you live in Maine or Massachusetts), to take the deduction, even if you obtain an extension to file your return.

Note: Even if eligible to make a deductible IRA contribution, you may want to forgo the deduction and instead fund a Roth IRA. You won't get an upfront deduction, but future income can become tax free (see Roth vs. Traditional IRA: Which Is Right for You?).

You can find the income limits for eligibility to make deductible IRA contributions if you're considered an active participant in a qualified retirement plan, as well as other IRA rules (including eligibility rules for Roth IRAs), in IRS Publication 590-A.

If you had a high-deductible health plan (HDHP) in 2015, you can contribute to a health savings account (HSA) as long as the funds are added by April 18, 2016 (April 19, if you live in Maine or Massachusetts), even if you get a filing extension. A high-deductible health plan is health coverage that contains certain minimum deductibles and maximum out-of-pocket expenses. Typically, the bronze plan from a government exchange meets the definition.

The deduction limit for 2015 is $3,350 for a self-only plan, or $6,650 for family coverage. You can add another $1,000 for anyone over age 55. For example, you and your spouse, both age 62, have family coverage. Your deduction limit for 2015 is $8,650 ($6,650 + $1,000 + $1,000). However, HSAs cannot be used once a person is enrolled in Medicare at age 65.

Usually if you had an HDHP for only part of the year, you have to prorate the maximum deduction. However, as long as you had an HDHP for all of December 2015 and you continue to have an HDHP for a certain period, you can make a full contribution to an HSA for 2015; no prorating is needed.

Note: If your employer made a contribution to your HSA, you cannot take the deduction; your employer can.

Details about HSAs are in the instructions to Form 8889.

If you are in business, including a sideline venture, you can make tax-deductible contributions to a qualified retirement plan, such as a 401(k) plan, a profit-sharing plan or a defined benefit (pension) plan. As long as the plan was set up by the end of 2015 (i.e., you signed the paperwork), you can make your contributions for the year by the extended due date of your return.

Didn't sign any paperwork? You can still set up and fund a SEP, a special type of retirement plan, up to the extended due date of your return. (See How does a Simplified Employee Pension (SEP) IRA work?.)

Find more information about qualified retirement plans in IRS Publication 560.

If you won't make the April 18 deadline ( April 19, if you live in Maine or Massachusetts), be sure to ask for a filing extension. You don't have to give a reason, but you do need to estimate what you think your final tax bill will be. By requesting an extension by April 18 (or 19), which gives you until October 17, 2016 for most taxpayers, to file your 2014 return, you'll avoid late filing penalties that could add to your tax liability for 2015. Use Form 4868 for this purpose. Click here for more information.

Asking for more time to file your 2015 return does not give you more time to pay what you owe for the year. Pay as much as you think you'll owe along with your extension request to minimize or avoid any late payment penalties.

As the clock ticks down to the filing deadline, don't delay taking any action that can save you money. Getting a filing extension may be advantageous, since it gives you more time to make tax-deductible contributions to certain qualified retirement plans (but not to IRAs). Remember: You'll still have to pay the tax due by April 18 (April 19 if you live in Maine or Massachusetts). Not sure whether any of these actions apply to you? Ask a tax pro. (For more on making the most of this year's tax return, read 10 Steps to Tax Preparation and Top 10 Filing Mistakes – And How to Avoid Them.)