Three Months Ended June 30, 2021 vs. Three Months Ended June 30, 2020
NOI for our Same-Store Community properties decreased 3.1%, or $6.3 million, for the three months ended June 30, 2021 compared to the same period in 2020. The decrease in property NOI was attributable to a 1.0%, or $3.0 million, decrease in property rental income and a 3.8%, or $3.3 million, increase in operating expenses. The decrease in property rental income was primarily driven by a 2.9%, or $8.2 million, decrease in rental rates and an increase of $3.8 million in rent concessions, partially offset by a decrease of $4.1 million in occupancy loss and a 7.5%, or $2.2 million, increase in reimbursement and ancillary and fee income. Physical occupancy increased by 1.1% to 97.2% and total monthly income per occupied home decreased 2.1% to $2,133.
The increase in operating expenses was primarily driven by a 18.4%, or $2.4 million, increase in repair and maintenance expense due to the increased use of third party vendors, a 4.3%, or $1.6 million, increase in real estate taxes, which was primarily due to higher assessed valuations, and a 22.4%, or $0.8 million, increase in insurance expense due to increased claims, partially offset by a 14.9%, or $2.3 million, decrease in personnel expense as a result of fewer employees.
The operating margin (property net operating income divided by property rental income) was 68.8% and 70.3% for the three months ended June 30, 2021 and 2020, respectively.
Six Months Ended June 30, 2021 vs. Six Months Ended June 30, 2020
NOI for our Same-Store Community properties decreased 6.9%, or $28.5 million, for the six months ended June 30, 2021 compared to the same period in 2020. The decrease in property NOI was attributable to a 3.8%, or $22.3 million, decrease in property rental income and a 3.6%, or $6.1 million, increase in operating expenses. The decrease in property rental income was primarily driven by a 2.9%, or $16.1 million, decrease in rental rates, a $4.6 million increase in our reserve on multifamily tenant lease receivables and an increase of $7.5 million in rent concessions, partially offset by a decrease of $2.1 million in occupancy loss and a 3.1%, or $1.9 million, increase in reimbursement and ancillary and fee income. Physical occupancy increased by 0.3% to 96.8% and total monthly income per occupied home decreased 4.1% to $2,125.
The increase in operating expenses was primarily driven by a 17.7%, or $4.5 million, increase in repair and maintenance expense due to the increased use of third party vendors, a 3.5%, or $2.5 million, increase in real estate taxes, which was primarily due to higher assessed valuations, and a 25.3%, or $1.8 million, increase in insurance expense due to increased claims, partially offset by a 12.4%, or $3.8 million, decrease in personnel expense as a result of fewer employees.
The operating margin (property net operating income divided by property rental income) was 68.6% and 70.8% for the six months ended June 30, 2021 and 2020, respectively.
Non-Mature Communities/Other
UDR’s Non-Mature Communities/Other represent those communities that do not meet the criteria to be included in Same-Store Communities, which include communities recently developed or acquired, redevelopment properties, sold or held for disposition properties, and non-apartment components of mixed use properties.
Three Months Ended June 30, 2021 vs. Three Months Ended June 30, 2020
The remaining 5.7%, or $11.9 million, of our total NOI during the three months ended June 30, 2021 was generated from our Non-Mature Communities/Other. NOI from Non-Mature Communities/Other increased by 29.5%, or $2.7 million, for the three months ended June 30, 2021 as compared to the same period in 2020. The increase was primarily attributable to a $2.7 million increase in stabilized, non-mature communities NOI due to operating communities acquired in 2021 and 2020 and a $2.3 million increase in acquired communities, partially offset by a $3.7 million decrease in sold and held for disposition communities.
Six Months Ended June 30, 2021 vs. Six Months Ended June 30, 2020
The remaining 6.2%, or $25.3 million, of our total NOI during the six months ended June 30, 2021 was generated from our Non-Mature Communities/Other. NOI from Non-Mature Communities/Other increased by 1.8%, or $0.5 million, for the six months ended June 30, 2021 as compared to the same period in 2020. The increase was primarily attributable to a $4.8 million increase in stabilized, non-mature communities NOI due to operating communities acquired in 2021 and 2020 and a