diff --git a/backfill_corrections/delphiBackfillCorrection/NAMESPACE b/backfill_corrections/delphiBackfillCorrection/NAMESPACE
index f1700be96..312bf2c0b 100644
--- a/backfill_corrections/delphiBackfillCorrection/NAMESPACE
+++ b/backfill_corrections/delphiBackfillCorrection/NAMESPACE
@@ -34,6 +34,7 @@ importFrom(dplyr,group_split)
 importFrom(dplyr,if_else)
 importFrom(dplyr,mutate)
 importFrom(dplyr,pull)
+importFrom(dplyr,rename)
 importFrom(dplyr,select)
 importFrom(dplyr,summarize)
 importFrom(dplyr,ungroup)
@@ -43,6 +44,7 @@ importFrom(lubridate,day)
 importFrom(lubridate,days_in_month)
 importFrom(lubridate,make_date)
 importFrom(lubridate,month)
+importFrom(lubridate,with_tz)
 importFrom(lubridate,year)
 importFrom(parallel,detectCores)
 importFrom(quantgen,quantile_lasso)
diff --git a/backfill_corrections/delphiBackfillCorrection/R/io.R b/backfill_corrections/delphiBackfillCorrection/R/io.R
index e16c90f0e..beb9c54cd 100644
--- a/backfill_corrections/delphiBackfillCorrection/R/io.R
+++ b/backfill_corrections/delphiBackfillCorrection/R/io.R
@@ -1,15 +1,84 @@
 #' Read a parquet file into a dataframe
 #' 
-#' @template input_dir-template
+#' @template input_file-template
 #'
 #' @importFrom arrow read_parquet
+#' @importFrom dplyr %>%
 #'
 #' @export
-read_data <- function(input_dir) {
-  df <- read_parquet(input_dir, as_data_frame = TRUE)
+read_data <- function(input_file) {
+  df <- read_parquet(input_file, as_data_frame = TRUE)
   return (df)
 }
 
+#' Add `issue_date` parsed from filename to daily input, if needed
+#'
+#' @param df dataframe containing input data from a single parquet file
+#' @template input_file-template
+#' @template indicator-template
+#' @template signal-template
+#' @template lag_col-template
+#' @template issued_col-template
+#'
+#' @importFrom stringr str_interp
+add_issue_date <- function(df, input_file, indicator, signal,
+  lag_col = "lag", issued_col = "issue_date") {
+  daily_pattern <- create_name_pattern(indicator, signal, "daily")
+  if (grepl(daily_pattern, input_file)) {
+    # Daily file
+    if (!(issued_col %in% names(df)) || any(is.na(df[[issued_col]]))) {
+      # Capture issue date from filename
+      issue_date <- as.Date(
+        sub("^.*/.*_as_of_([0-9]{8})[.]parquet$", "\\1", input_file),
+        format = "%Y%m%d"
+      )
+      df[[issued_col]] <- issue_date
+    }
+  } else {
+    # Rollup file
+    if (!(lag_col %in% colnames(df)) && !(issued_col %in% colnames(df))) {
+      stop("since rollup files contain data spanning multiple issues, ",
+           "the issue date field cannot be reconstructed from the ",
+           "filename. Thus, either issue date or lag must be ",
+           str_interp("provided in the input file ${input_file}"))
+    }
+    if (!(issued_col %in% colnames(df))) {
+      df[[issued_col]] <- as.Date(df$time_value + df[[lag_col]])
+    }
+  }
+
+  return(df)
+}
+
+#' Add `lag` field based on issue date and time value, if needed
+#'
+#' @param df dataframe containing input data from a single parquet file
+#' @template lag_col-template
+#' @template issued_col-template
+add_lag <- function(df, lag_col = "lag", issued_col = "issue_date") {
+  if ( (lag_col %in% colnames(df) && any(is.na(df[[lag_col]]))) ||
+    !(lag_col %in% colnames(df)) ) {
+    df[[lag_col]] <- as.integer(df[[issued_col]] - df$time_value)
+  }
+
+  return(df)
+}
+
+#' Extract date from datetime column in timezone-aware way
+#'
+#' @param df dataframe containing input data from a single parquet file
+#' @param cols vector of names of datetime fields to convert to date
+#'
+#' @importFrom lubridate with_tz
+datetime_to_date <- function(df, cols = c("time_value", "issue_date")) {
+  for (col in cols) {
+    if (col %in% colnames(df)) {
+      df[[col]] <- as.Date(with_tz(df[[col]], "UTC"))
+    }
+  }
+  return(df)
+}
+
 #' Export the result to customized directory
 #'
 #' @param test_data test data containing prediction results
diff --git a/backfill_corrections/delphiBackfillCorrection/R/main.R b/backfill_corrections/delphiBackfillCorrection/R/main.R
index 8a67cb6e7..557d0ed28 100644
--- a/backfill_corrections/delphiBackfillCorrection/R/main.R
+++ b/backfill_corrections/delphiBackfillCorrection/R/main.R
@@ -227,7 +227,7 @@ run_backfill <- function(df, params,
 #' 
 #' @template params-template
 #'
-#' @importFrom dplyr bind_rows mutate
+#' @importFrom dplyr bind_rows mutate rename
 #' @importFrom parallel detectCores
 #' @importFrom rlang .data
 #' 
@@ -287,9 +287,15 @@ main <- function(params) {
     msg_ts("Reading in and combining associated files")
     input_data <- lapply(
       files_list,
-      function(file) {read_data(file)}
+      function(file) {
+        read_data(file) %>%
+        datetime_to_date() %>%
+        add_issue_date(file, input_group$indicator, input_group$signal) %>%
+        add_lag()
+      }
     ) %>%
-      bind_rows()
+      bind_rows() %>%
+      rename(geo_value = .data$fips)
 
     if (nrow(input_data) == 0) {
       warning(str_interp(
diff --git a/backfill_corrections/delphiBackfillCorrection/R/utils.R b/backfill_corrections/delphiBackfillCorrection/R/utils.R
index 550b84f50..5c50a4ef7 100644
--- a/backfill_corrections/delphiBackfillCorrection/R/utils.R
+++ b/backfill_corrections/delphiBackfillCorrection/R/utils.R
@@ -148,12 +148,9 @@ validity_checks <- function(df, value_type, num_col, denom_col, signal_suffixes,
     stop("No 'time_value' column detected for the reference date!")
   }
   
-  # issue_date or lag should exist in the dataset
-  if ( !lag_col %in% colnames(df) ) {
-    if ( issued_col %in% colnames(df) ) {
-      df$lag = as.integer(df$issue_date - df$time_value)
-    }
-    else {stop("No issue_date or lag exists!")}
+  # issue_date and lag should exist in the dataset
+  if ( !(lag_col %in% colnames(df)) || !(issued_col %in% colnames(df))) {
+    stop("issue_date and lag fields must exist in the input data")
   }
 
   return(list(df = df, value_cols = value_cols))
diff --git a/backfill_corrections/delphiBackfillCorrection/man-roxygen/input_file-template.R b/backfill_corrections/delphiBackfillCorrection/man-roxygen/input_file-template.R
new file mode 100644
index 000000000..2067a050d
--- /dev/null
+++ b/backfill_corrections/delphiBackfillCorrection/man-roxygen/input_file-template.R
@@ -0,0 +1,2 @@
+#' @param input_file path to the an individual file containing input data
+#'   in `.parquet` format.
diff --git a/backfill_corrections/delphiBackfillCorrection/man/add_issue_date.Rd b/backfill_corrections/delphiBackfillCorrection/man/add_issue_date.Rd
new file mode 100644
index 000000000..7f53fc0a3
--- /dev/null
+++ b/backfill_corrections/delphiBackfillCorrection/man/add_issue_date.Rd
@@ -0,0 +1,38 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/io.R
+\name{add_issue_date}
+\alias{add_issue_date}
+\title{Add `issue_date` parsed from filename to daily input, if needed}
+\usage{
+add_issue_date(
+  df,
+  input_file,
+  indicator,
+  signal,
+  lag_col = "lag",
+  issued_col = "issue_date"
+)
+}
+\arguments{
+\item{df}{dataframe containing input data from a single parquet file}
+
+\item{input_file}{path to the an individual file containing input data
+in `.parquet` format.}
+
+\item{indicator}{string specifying the name of the indicator as used in
+`parquet` input data filenames. One indicator can be associated
+with multiple signals.}
+
+\item{signal}{string specifying the name of the signal as used in
+`parquet` input data filenames. One indicator can be associated
+with multiple signals.}
+
+\item{lag_col}{string specifying name of lag field within
+the input dataframe.}
+
+\item{issued_col}{string specifying name of issue date (version) field within
+the input dataframe.}
+}
+\description{
+Add `issue_date` parsed from filename to daily input, if needed
+}
diff --git a/backfill_corrections/delphiBackfillCorrection/man/add_lag.Rd b/backfill_corrections/delphiBackfillCorrection/man/add_lag.Rd
new file mode 100644
index 000000000..b4779c1a7
--- /dev/null
+++ b/backfill_corrections/delphiBackfillCorrection/man/add_lag.Rd
@@ -0,0 +1,20 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/io.R
+\name{add_lag}
+\alias{add_lag}
+\title{Add `lag` field based on issue date and time value, if needed}
+\usage{
+add_lag(df, lag_col = "lag", issued_col = "issue_date")
+}
+\arguments{
+\item{df}{dataframe containing input data from a single parquet file}
+
+\item{lag_col}{string specifying name of lag field within
+the input dataframe.}
+
+\item{issued_col}{string specifying name of issue date (version) field within
+the input dataframe.}
+}
+\description{
+Add `lag` field based on issue date and time value, if needed
+}
diff --git a/backfill_corrections/delphiBackfillCorrection/man/datetime_to_date.Rd b/backfill_corrections/delphiBackfillCorrection/man/datetime_to_date.Rd
new file mode 100644
index 000000000..8d5e2c409
--- /dev/null
+++ b/backfill_corrections/delphiBackfillCorrection/man/datetime_to_date.Rd
@@ -0,0 +1,16 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/io.R
+\name{datetime_to_date}
+\alias{datetime_to_date}
+\title{Extract date from datetime column in timezone-aware way}
+\usage{
+datetime_to_date(df, cols = c("time_value", "issue_date"))
+}
+\arguments{
+\item{df}{dataframe containing input data from a single parquet file}
+
+\item{cols}{vector of names of datetime fields to convert to date}
+}
+\description{
+Extract date from datetime column in timezone-aware way
+}
diff --git a/backfill_corrections/delphiBackfillCorrection/man/read_data.Rd b/backfill_corrections/delphiBackfillCorrection/man/read_data.Rd
index 1b5f24726..40335fd35 100644
--- a/backfill_corrections/delphiBackfillCorrection/man/read_data.Rd
+++ b/backfill_corrections/delphiBackfillCorrection/man/read_data.Rd
@@ -4,10 +4,11 @@
 \alias{read_data}
 \title{Read a parquet file into a dataframe}
 \usage{
-read_data(input_dir)
+read_data(input_file)
 }
 \arguments{
-\item{input_dir}{path to the directory containing input data}
+\item{input_file}{path to the an individual file containing input data
+in `.parquet` format.}
 }
 \description{
 Read a parquet file into a dataframe