You may carry over only that portion of the credit that you do not apply to tax. You cannot carry over any amount that you paid that was more than the amount allowed as a credit.
For example: last year, John, a single person, paid $400 to School A for extra curricular activity fees for Johns child. Last year, John is allowed a credit of $200. His tax due was $100. John may carryover $100 of the unused $200 credit to this year. John cannot claim any credit for the $200 fee he paid that was more than the allowable credit ($400 minus allowable credit of $200).
Fees Paid to Public Schools
Beginning 2014, you must also complete Arizona Form 301, Nonrefundable Individual Tax Credits and Recapture, and include Forms 301 and 322 with your tax return to claim this credit.
Arizona law provides a credit for cash contributions made and for certain fees paid to public schools in Arizona. The credit for contributions made or fees paid to a public school must be claimed in the year of the donation.
The credit is equal to the amount contributed or the amount of fees paid. For single taxpayers or heads of household, the credit cannot exceed $200. For married taxpayers that file a joint return, the credit cannot exceed $400. In most cases, for married taxpayers who file separate returns, each spouse may claim only one-half (1/2) of the credit that would have been allowed on a joint return.
Arizona Form 322