Roth IRA phase out amounts

Before I start working out the problem on my own I was wondering if anyone out there has put together a worksheet that calculates the amount of money you can contribute to a Roth IRA when your modified AGI falls within the phase out zone. The rules for this are as follows.

## Amount of your reduced Roth IRA contribution

If the amount you can contribute must be reduced, figure your reduced contribution limit as follows.

1. Start with your modified AGI. 2. Subtract from the amount in (1):

* $204,000 if filing a joint return or qualifying widow(er), * $-0- if married filing a separate return, and you lived with your spouse at any time during the year, or * $129,000 for all other individuals.

1. Divide the result in (2) by $15,000 ($10,000 if filing a joint return, qualifying widow(er), or married filing a separate return and you lived with your spouse at any time during the year). 2. Multiply the maximum contribution limit (before reduction by this adjustment and before reduction for any contributions to traditional IRAs) by the result in (3). 3. Subtract the result in (4) from the maximum contribution limit before this reduction. The result is your reduced contribution limit.

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I can definitely follow this to work out what my limit for a Roth contribution is, but thought I would ask in case someone else out there had already put such a thing together. Does such a thing exist or should I just go ahead and make my own spreadsheet for this?