Donations are only deductible in the year made.
If your donation of non-cash items is more than 60% of your AGI, your deduction is limited and the remainder will automatically carry forward to next year. But you can't choose to carry your deductions forward, it either will or won't be required based on the type of donation and the type of exempt organization you donated to. And you must list the donation in the year actually made, and see if you hit one of the limits.
Also beware, you can't claim a deduction of more than $5000 for a single item or "group of similar items" unless you have a signed appraisal, and you get a financially responsible officer of the charity and the appraiser to sign a copy of form 8283 confirming the donation, which you have to mail to the IRS after e-filing the rest of your return. There is no specific guidance on what constitutes a "group of similar items", but certainly, "used household goods", "used clothing", and "used furniture" could be 3 reasonable groups. Without an appraisal, your deduction is limited to $5000 per group of similar items, no matter how valuable they were.
