If you’re trying to get your financial house in order, here’s a tip: Grab a calendar. With a little planning and a few phone calls, you can make it easier to pay your bills on time.

Just keeping track of when your bills are due can help a lot. What you may not realize is that if the dates aren’t convenient, some of them can be changed. Often a simple request is all it takes to change the due date for credit cards, car loans and other consumer loans and even for your telephone bill.

And if a good chunk of your income comes from investments, you may be able to rearrange your portfolio to produce dividend or interest income right when you need it.

The first step to getting cash flow under control is to mark up a calendar, noting the days you collect your paychecks or other payments and the due dates for various bills.

“A calendar is the best bill-paying tool available,” said Joanne Whittlesey, a counselor with Consumer Credit Counseling Service. She recommends using a calendar in conjunction with a worksheet, budgeting spending over two to three months at a time.

That alone is enough to put some people on the right track. They can leave money in their checking accounts, mentally earmarking it for future bills, and it will be available when they need it. But many others cannot resist the temptation to spend more in the weeks when they have excess cash, then find themselves short when the bills come due. For them, it is easier to smooth out cash flow by timing expenses to match their income.

Flexibility of payment dates is one of the features Capital One promotes in television commercials for its “no hassle credit card.” One spot shows a mountain climber abandoning his quest and rushing back to base camp so he can get his payment in on time. At Capital One you have your choice of payment due dates, the ad says.

Although they may not promote it, many other card issuers offer the same option.

“People just have to call our customer service hot lines and changes can be made available two cycles after they’re requested,” said Mary Beth Navarro, spokeswoman for First Union/Wachovia. You can change the due date for your car payment the same way, she said.

Such requests are common, said James Underwood, spokesman for AmSouth Bank.

“We do that all the time,” he said. “People don’t want a payment date to be the 12th or 13th if they get paid on the 15th. We have the flexibility of moving that date around. Even if they start with one date and their pay schedule changes, we can adjust.”

Banks typically are less flexible on mortgage payments, but they still offer some choices.

At Bank of America, for example, if you sign up for mortgage payments through an automatic transfer from your checking account, you can choose any of the first 10 days of the month for the transfer, said Paul Ramos, the bank’s mortgage manager for the Tampa Bay, Fla., area. “A lot of lenders now have automatic payment withdrawals that allow customers to make payments on days other than the first,” he said.

Whatever the bill, it doesn’t hurt to ask for a billing cycle you would find more convenient. Many service providers, including Verizon, say they are glad to accommodate customers.

But you are not likely to get a “yes” answer if you try to change the due date for your water or electric bills. Because they are based on a meter reading, you and your neighbors probably are going to have your meters read and your bills generated about the same time, like it or not.

Switching due dates and keeping a calendar is not the solution to every bill-paying problem.

“It’s not going to solve anybody’s problem if they don’t have enough money to go around in the first place,” Whittlesey, credit counselor, said.