The Consumer Reports Money Lab found that, with most spend

Saving money is tough for many people, so bank programs designed to help consumers save every time they spend can be tempting. Under those plans, money is deposited into a savings or money-market account when purchases are made with a debit or credit card.

But according to Consumer Reports, saving money by spending it is as unprofitable as it sounds. The Consumer Reports Money Lab, which crunched the numbers, shows why:

Bank of America’s Keep the Change

Consumers set up a savings or money-market account and link it to a checking account with a debit card.

With each purchase that’s made with the card, the bank rounds the amount up to the nearest dollar and transfers the difference to the savings account. If someone spends $332.49, for example, Bank of America will transfer 51 cents from checking to savings.

The bank also matches the transfer amount at 100 percent for the first three months and at 5 percent thereafter, up to $250 a year, which is taxable. Assuming the average transaction is 50 cents, someone would have to make 1,728 debit purchases in the first year to get the full $250, according to Bank of America’s online calculator. But because the amount matched drops, someone would have to make 10,000 transactions in the second year to get the $250.

The basic savings account recently paid a paltry 0.20 percent interest, and the money-market account paid 1.75 percent on deposits of less than $5,000, at a time when many online savings accounts were paying more than 3 percent.

And if an automatic transfer results in an overdraft, users are socked with a $25 fee unless they sign up for overdraft protection, in which case they’d be charged $10 each time.

CR’s bottom line: Consumers will do better saving in accounts that pay more interest.

Wachovia’s Way2save

Consumers set up linked savings and checking accounts, and Wachovia moves $1 from checking to savings every time they make a debit purchase or pay a bill online. The bank doesn’t match the transfers but pays 5 percent interest on the savings account for the first year and a 5 percent bonus on the savings balance at the end of the year. At the start of year two, consumers get 2 percent interest and a 2 percent bonus. Additional deposits into the account are limited to $100 a month.

Someone who transferred $100 a month into savings would earn $92 in interest and bonuses the first year, in addition to the $1 transfers from debit transactions.

But getting the maximum $300 bonus would require depositing $1,200 and making 4,800 transactions in the first year. The bonus is paid for three years and is taxable.

CR’s bottom line: This program isn’t going to add much to a consumer’s net worth.

American Express One

This credit card pays 1 percent cash back on purchases and a $50 bonus after the first purchase. The cash goes into a savings account, which recently paid 2.75 percent.

There’s no limit on the rewards that can be earned. And the card doesn’t charge interest on new purchases, only on the previous month’s balance. But a $35 annual fee kicks in after the first year, so someone would have to charge $3,500 to break even.

CR’s bottom line: A consumer might do better with a card with greater rewards (some pay 3 percent or more for various spending categories) that charges no annual fee.