Q. We’ve been using a SARSEP for our business. With the new rules for DB(k)s in place, are these still valid?

The “Worker, Homeownership and Business Assistance Act” includes a powerful tax-saver for struggling business owners. It extends and expands the earlier Stimulus Act’s tax break for net operating losses. Strategy: Let the tax law do double duty. If you qualify, you can take advantage of the enhanced NOL carryback rules for both 2008 and 2009. A business that carries back an NOL to a profitable tax year is entitled to a quick tax refund from the IRS.

The end of the year came and went without formal approval of the “Tax Extenders Act of 2009.” But once enacted, the new law would retroactively extend a bunch of key tax provisions that expired after 2009. Generally, it will preserve these tax benefits for one more year. Here are the main tax winners for individuals and businesses:

Maybe you’re not planning to move anytime soon despite the new homebuyer credit. As long as you’re staying put, you might decide to invest some money into the house. But you generally receive no current tax benefit from home improvements. Strategy: Make home improvements needed for medical reasons. If certain requirements are met, you can deduct a portion of the cost this year.

You may not realize it, but many small business owners adopt war principles to lead their companies to higher profits. Think about it:

Q. I transferred mutual fund shares worth $3,000 to my niece for her graduation. My basis was $2,500. If she sells the shares for $2,200, can she deduct the full loss?

Besides the new DB(k) plan option, small business owners can choose from a wide variety of qualified retirement plans, subject to a bewildering array of rules. Now the IRS wants to help you chart your course. It has launched a new online resource called the Retirement Plans Navigator.

The IRS recently announced that taxpayers who claim the first-time homebuyer credit on their 2009 returns cannot file electronically. Also, the agency has revised Form 5405, First-Time Homebuyer Credit, to reflect new law changes.

Roth IRA conversions aren’t just for older taxpayers in 2010. Suppose your 20-year-old has $25,000 in a traditional IRA. If he or she converts to a Roth this year, the tax may be limited to $3,750 (15% of $25,000), spread out over the next two years.

How can you check out a charitable organization’s status? The easiest way is to investigate it online. (Tip: Just having an “.org” extension isn’t enough.) Here are three top resources:

Q. I’m the sole beneficiary of my late spouse’s 401(k) with Prudential. Do I rename the beneficiaries if I transfer ownership to my name?

Q. Our 21-year-old son received a $45,000 inheritance from his grandmother in 2009. Can we still claim him as our dependent?

Q. My husband is on a special diet because of a medical condition. Can we deduct his food as a medical expense?

A family limited partnership (FLP) may be used to protect business interests from creditors. Assuming no ready market for the shares transferred to the FLP, the value can be discounted for estate and gift tax purposes. The IRS often challenges these discounts. In a new case, the IRS questioned the legitimacy of a transfer to a FLP shortly before the grantor’s death:

Economic confidence among owners of America’s smallest businesses fell last month to its lowest level since February, as more owners cited serious concerns about cash flow, according to the Discover Small Business Watch survey of 750 microbusinesses. This is more evidence that the small business economy is lagging behind Fortune 500s on the road to economic recovery.

The tax law contains a break for investing in qualified small business stock (QSBS). If certain requirements are met (e.g., the stock must be held five years), you can exclude (pay no tax on) up to 50% of the gain. The capital gains tax rate for QSBS is 28%, so the effective tax rate is 14% (50% of 28%). Now the new economic stimulus law has sweetened the deal.

The IRS recently announced the new “standard mileage rates” that you can use in 2010 without keeping detailed records of your vehicle travel expenses. Mild surprise: The new rates are lower or the same as the rates for 2009.

As an owner of the company, you’re probably entitled to your fair share of perks (p’s) and qualified benefits (q’s). Generally, the perks you receive, which are not available to other employees, are taxable as compensation. However, qualified bennies offered to the entire workforce are generally tax-free. Here’s a quick rundown:

Keeping detailed records of employee travel expenses is a hassle. But there’s a way you can simplify matters for your small business without any tax downside. Strategy: Have your private company use the IRS-approved “per diem rates” for federal government employees. This way, employees don’t have to account for every cup of coffee or cab ride.

A new defense appropriations law extends the COBRA premium subsidy for up to 15 months and also allows it for employees who are “involuntarily terminated” in January and February of this year.

As a small business owner, you have plenty of options if you want to provide a qualified retirement plan for your company. But now there’s a new kid on the block: Consider the defined benefit 401(k) plan (DB(k)). This hybrid plan blends advantages of a traditional pension plan with a regular 401(k) and becomes available on Jan. 1, 2010.

Q. I have invested in several T. Rowe Price mutual funds. Will I have to pay tax on capital gain distributions if a fund has a loss for the year?

Normally, you can't deduct investment losses inside an IRA. But there's a way you still might claim an IRA loss this year.

Q. I am age 72 and operate a sole proprietorship generating about $50,000 in net income. Can I contribute the $50,000 to my Roth 401(k) and then roll it over tax-free into a Roth IRA?

In rapid-fire succession, the Senate and House passed significant new legislation in early November, extending unemployment benefits and adding certain tax-based incentives. On Nov. 6 the president officially signed the fast-track new law—the “Worker, Homeownership, and Business Assistance Act of 2009.” Among the key tax changes, the new law expands and extends the tax credit for “first-time homebuyers” and the longer carryback period for NOLs.