Alimony recapture is the IRS's attempt to uncover and penalize front-loaded property transfers disguised as alimony payments. I.R.C. § 71(f). In particular, the IRS looks at the first three years of alimony payments and notes if the amounts seem to be decreasing.  When that's the case, the table is turned on the alimony payer: The payer includes the recapture amount in income (previously deducted) and the recipient gets an above-the-line deduction (previously included in income).

Given the alimony payment amount in the first three years, this Excel workbook figures if alimony needs to be recaptured, and if so, what amount. 

As always, doublecheck this workbook's calculations.

At times it's useful to have the IRC at your fingertips without being online. The US government helpfully posts an up-to-date copy of the US Code, including Title 26 (IRC) online and makes it available for download as a single large text file. 

You can save it as a text file file on your computer, but you can also try "printing" it to PDF for extended search, bookmarking, and annotation capabilities.  Use Google Chrome for Print to PDF functionality. Careful: the PDF will have more than 9000 pages and will take a while to produce (if at all).

When searching for particular code sections on your downloaded file, click CTRL-F and type "sec. xxx ".  For example, "sec. 61 ".  Note the extra space after the code section - this will ensure you only get your specified code section, and not all the ones that start with the same numbers.

Good luck!