It's been a cold winter for shareholders of Intuit ( INTU).

The stock is off nearly 15% from its October highs as Wall Street worries that its $1.35 billion takeover of Digital Insight ( DGIN) could take the tax and accounting software provider too far afield.

But with tax season rapidly approaching, Citigroup analyst Brent Thill has upgraded the stock to buy, saying Intuit's valuation of 24 times forward earnings is now attractive, and he figures the stock could reach $36 -- an upside of about 17%. (The consensus target price of analysts who follow the stock is a bit lower -- $35.25, according to Thomson First Call.)

On a day when tech stocks were tumbling, Thursday's upgrade gave Intuit a modest boost; in recent trading shares were up 25 cents, or about 1%, to $30.83.

Thill notes that over the last two years the stock has been weak in January, "but has returned approximately 20% from early February through mid-July as tax data comes in strong." He believes the company is gaining market share and he expects growth of 17% in its core tax business; Intuit's guidance calls for growth of 10% to 15%. Tax revenue increased 24.5% last fiscal year, about double that of guidance.

Announced in late November, the Digital Insight acquisition is expected to close in February. The company sells software that allows customers to interact with their online banking accounts. A much smaller acquisition of Electronic Clearing House ( ECHO) is also pending. The two companies could add a total of $180 million to the top line over the balance of fiscal 2007, says Thill.

Citigroup has an investment banking relationship with Intuit.