What is the step-by-step source for the amount entered on Schedule A line 5c? The form has an extra $10,000 added for personal property taxes.

[Critter]

That is an amount you entered yourself which is probably wrong since it should be more like $100 if anything at all  ... switch to the FORMS mode, click on that amount to data source it and find out where you made the data entry error. 

https://www.irs.gov/pub/irs-pdf/f1040sa.pdf

[rory]

I went ahead and entered $0 on the worksheet even though the $10,000 was not on the form.  It did zero out the amount on Schedule A 5c.  Must be some kind of bug.

[SweetieJean]

Line 5c are the state and local personal property taxes you paid, but only if the taxes were based on value alone and were imposed on a yearly basis.

Example: You paid a yearly fee for the registration of your car. Part of the fee was based on the car's value and part was based on its weight. State and Local Personal Property Taxes Enter on line 5c the state and local personal property taxes you paid, but only if the taxes were based on value alone and were imposed on a yearly basis. Example. You paid a yearly fee for the registration of your car. Part of the fee was based on the car's value and part was based on its weight.  You can deduct only the part of the fee that was based on the car's value. 

It sounds like you entered Real Estate (property) taxes here by mistake.

[rory]

On the step-by-step, both Car Registration Fees and Personal Property Taxes are $0.  On the Schedule A Tax & Int Worksheet, 3a State and Local Property Taxes does not have any entries.

[Critter]

Line 5E will probably the $10000 limit this year ... do not override that amount.

[SweetieJean]

Be sure to run a software update.