It was a sweet offer: free checking for life. For customers of the

Bank of New York

(BK) - Get Report

, however, life could end early.

That's because

JPMorgan Chase

(JPM) - Get Report

, which inked a deal April 8 to buy all of Bank of New York's 338 retail branches, hasn't committed itself to honoring the pledge.

Officials with JPMorgan say it's too soon to say what will happen to the accounts of customers who received the lifetime guarantee. The $3.1 billion deal, in which JPMorgan Chase is swapping its corporate trust business for Bank of New York's branches, is expected to close later this year.

Tom Kelly, a JPMorgan Chase spokesman, says the nation's third-largest bank won't make any decision until it completes a "product-by-product comparison'' of itself and Bank of New York. That process won't happen for a while. But Kelly notes that JPMorgan Chase already offers no-fee checking to many qualified customers.

JPMorgan Chase doesn't offer anything directly comparable to Bank of New York's lifetime pledge however.

The unusual "free-for-life checking'' deal, in which Bank of New York promises not to assess any monthly maintenance fees, has been the centerpiece of the lender's advertising campaign for the past two years. The offer is credited with luring new retail customers to the nation's oldest bank, which reports having 600,000 household accounts.

On its Web site, the Bank of New York touts its no-fee checking arrangement as "a deal that will last for the rest of your life.''

The fate of the lifetime guarantee is just one of the many customer-service issues that the banks will need to hash out before the merger is complete. Given that much of banking is a relationship business, industry experts say it's important for acquiring banks not to rush in and do things that offend existing customers.

Some say JPMorgan's decision on how it handles the lifetime guarantee could go a long way in determining whether it's able to keep Bank of New York customers from moving their business to another lender.

"What I've always told clients is, you want to make sure that the customers you are picking up, at worst, feel neutral after a deal,'' says Richard Kelly, an investment banker with Sanders Morris Harris who specializes in advising on banking mergers. "But what you really want is for them to feel better.''

If JPMorgan ultimately decides not to honor the pledge, it will probably bow out slowly, says Kelly, the investment banker. He says doesn't expect the bank to make any rash decisions.

"If they are going to introduce fees with those accounts, they won't do it in one fell swoop,'' says Kelly, the Sanders Morris banker.

Yet it's also true that consumers tend to be creatures of habit, and it can take an awful lot to irritate them enough to move to another company. One thing banks and other financial services companies that make acquisitions often count on is that people exhibit inertia when it comes to moving accounts.

For its part, Bank of New York says it has no plans to stop offering the free-for-life checking guarantee before the current promotion expires on July 14. The bank, which also is offering to give back $200 to customers who take advantage of the deal and meet other criteria, says it's business as usual until the agreement with JPMorgan is completed.

"It's anticipated that Chase will honor the existing promotions,'' says Kevin Heine, a Bank of New York spokesman. "It's too early to say definitely.''