80% tax rate isn't a record its relatively simple now to achieve 99% tax marginal rate if you want to be generous to hmrc - i am presuming you are not of that ilk though so lets see whats up.
When i fill in my self assessment tax return I'm pretty sure my employer has dealt with all tax owed on the £150k (hopefully I'm not wrong here)
Generally speaking one should never
presume the paye tax code corrects the correct amount of tax during the year - not sure why hmrc don't advertise this fact much but it is often impossible to correctly predict how the number will pan out.
This is particularly common with individuals who go over the 100k / 150k threshold and have coding notice adjustments - hmrc will often not know what marginal rate you will end up in come the end of the year. The main losers in this regard are individuals who go over the 100k in a tax year when they were previously below and receive personal allowance via tax code they were not entitled to (hmmm are they losing by underpaing tax in year ??)
Best bet if you are unsure is enter employment related details first only and do the calcs and see how things end up.
You should always pay particular attention to your tax code too - you need to look at what was included in your tax code and see whether it was cumulative or not. (Ie not w1/m1)
Note your tax code should not include any personal allowance
Note as you earn over 150k potentially you could have additional pension related tax charges if you put more than 10k into a pension (from all sources) or your pension pot grew by more than the limit allowed if that is how your pension restrictions and calculated - presumably this additional restriction is not an issue - NHS staff are often have problems in this regard.
I would not expect the tax rate on the property income itself to be more than 45% of the 10k as long as deductibles are not finance fees -if deductibles are finance fees - then at most this would add an extra £125 to your bill (25% of 25% of the finance costs)
tax rates available here
It deffo sound like you have messed up or there is something paye related here - more likely a paye related issue
feel free to post tax code details here and secondly check that tax deducted at source matches up with hmrc tables.
you may want to double check you haven't made a numpty mistake like entering gross salary rather than p60 taxable pay total - (reminds me of my numpty bike clown fixing days when my bike pedal fell of when i was far from home - i screwed it back on with my fingers carefully only to find out i now had a clown type bike with both pedals pointing up or down at the same time)